ERROR in multi ./node_modules/@fortawesome/fontawesome-free/scss/fontawesome.scss ./node_modules/@fortawesome/fontawesome-free/scss/solid.scss ./node_modules/@fortawesome/fontawesome-free/scss/regular.scss ./node_modules/@fortawesome/fontawesome-free/scss/brands.scss ./node_modules/ng-uikit-pro-standard/assests/scss/bootstrap/bootstrap.scss ./node_modules/ng-uikit-pro-standard/assets/scss/mdb.scss ./src/styles.scss
Module not found: Error: Can't resolve '/home/cparrish/sandbox/phoenix/node_modules/ng-uikit-pro-standard/assests/scss/bootstrap/bootstrap.scss' in '/home/cparrish/sandbox/phoenix'

I removed the install of MDB above but here it is in Package.json

{
  "name": "phoenix",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^7.2.9",
    "@angular/common": "^7.2.9",
    "@angular/compiler": "^7.2.9",
    "@angular/core": "^7.2.9",
    "@angular/forms": "^7.2.9",
    "@angular/http": "^7.2.9",
    "@angular/platform-browser": "^7.2.9",
    "@angular/platform-browser-dynamic": "^7.2.9",
    "@angular/router": "^7.2.9",
    "@fortawesome/fontawesome-free": "^5.8.0",
    "@ngtools/webpack": "^7.3.5",
    "@types/chart.js": "^2.7.49",
    "chart.js": "^2.5.0",
    "core-js": "^2.5.4",
    "easy-pie-chart": "^2.1.7",
    "hammerjs": "^2.0.8",
    "jasmine-marbles": "^0.4.1",
    "ng-uikit-pro-standard": "git+https://mytoken@git.mdbootstrap.com/mdb/angular/ng-uikit-pro-standard.git",
    "rxjs": "~6.4.0",
    "screenfull": "^3.3.0",
    "zone.js": "^0.8.26"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "^0.13.6",
    "@angular/cli": "^7.3.5",
    "@angular/compiler-cli": "^7.2.10",
    "@angular/language-service": "^7.2.9",
    "@types/jasmine": "~2.8.8",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "^5.0.0-beta.1",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "^4.0.1",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.1",
    "karma-jasmine": "~1.1.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.4.0",
    "ts-node": "~7.0.0",
    "tslint": "^5.14.0",
    "typescript": "^3.1.1"
  }
}

It looks like everything is configured correctly (I'm not sure about package.json and MDB installation because there is something wrong with the code snippet you provided). Please try to remove node_modules and package-lock.json, run npm install again and let me know if that helped.

npm ls --depth=0
phoenix@0.0.0 /home/cparrish/sandbox/phoenix
├── @angular-devkit/build-angular@0.13.6
├── @angular/animations@7.2.10
├── @angular/cli@7.3.6
├── @angular/common@7.2.10
├── @angular/compiler@7.2.10
├── @angular/compiler-cli@7.2.10
├── @angular/core@7.2.10
├── @angular/forms@7.2.10
├── @angular/http@7.2.10
├── @angular/language-service@7.2.10
├── @angular/platform-browser@7.2.10
├── @angular/platform-browser-dynamic@7.2.10
├── @angular/router@7.2.10
├── @fortawesome/fontawesome-free@5.8.1
├── @ngtools/webpack@7.3.6
├── @types/chart.js@2.7.49
├── @types/jasmine@2.8.16
├── @types/jasminewd2@2.0.6
├── @types/node@8.9.5
├── chart.js@2.8.0
├── codelyzer@5.0.0-beta.1
├── core-js@2.6.5
├── easy-pie-chart@2.1.7
├── hammerjs@2.0.8
├── jasmine-core@2.99.1
├── jasmine-marbles@0.4.1
├── jasmine-spec-reporter@4.2.1
├── karma@4.0.1
├── karma-chrome-launcher@2.2.0
├── karma-coverage-istanbul-reporter@2.0.5
├── karma-jasmine@1.1.2
├── karma-jasmine-html-reporter@0.2.2
├── protractor@5.4.2
├── rxjs@6.4.0
├── screenfull@3.3.3
├── ts-node@7.0.1
├── tslint@5.14.0
├── typescript@3.1.1
└── zone.js@0.8.26

ng version

 _                      _                 ____ _     ___
/ \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|

/ △ \ | '_ \ / _| | | | |/ _ | '| | | | | | | / \| | | | (| | || | | (| | | | || | | | // __| ||__, |__,||__,|| __**|_|_| |**_/

Angular CLI: 7.3.6Node: 10.0.0OS: linux x64Angular: 7.2.10... animations, common, compiler, compiler-cli, core, forms... http, language-service, platform-browser... platform-browser-dynamic, router

Package Version

@angular-devkit/architect 0.13.6@angular-devkit/build-angular 0.13.6@angular-devkit/build-optimizer 0.13.6@angular-devkit/build-webpack 0.13.6@angular-devkit/core 7.3.6@angular-devkit/schematics 7.3.6@angular/cli 7.3.6@ngtools/webpack 7.3.6@schematics/angular 7.3.6@schematics/update 0.13.6rxjs 6.4.0typescript 3.1.1webpack 4.29.0

angular.json

{
  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
  "version": 1,
  "newProjectRoot": "projects",
  "projects": {
    "phoenix": {
      "root": "",
      "sourceRoot": "src",
      "projectType": "application",
      "prefix": "pa",
      "schematics": {
        "@schematics/angular:component": {
          "styleext": "scss",
          "prefix": "pa"
        },
        "@schematics/angular:directive": {
          "prefix": "pa"
        }
      },
      "architect": {
        "build": {
          "builder": "@angular-devkit/build-angular:browser",
          "options": {
            "outputPath": "dist/phoenix",
            "index": "src/index.html",
            "main": "src/main.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "src/tsconfig.app.json",
            "assets": [
              "src/favicon.ico",
              "src/assets"
            ],
            "styles": [
              "node_modules/@fortawesome/fontawesome-free/scss/fontawesome.scss",
              "node_modules/@fortawesome/fontawesome-free/scss/solid.scss",
              "node_modules/@fortawesome/fontawesome-free/scss/regular.scss",
              "node_modules/@fortawesome/fontawesome-free/scss/brands.scss",
              "node_modules/ng-uikit-pro-standard/assests/scss/bootstrap/bootstrap.scss",
              "node_modules/ng-uikit-pro-standard/assets/scss/mdb.scss",
              "src/styles.scss"
            ],
            "scripts": [
              "node_modules/chart.js/dist/Chart.js",
              "node_modules/easy-pie-chart/dist/easypiechart.js",
              "node_modules/screenfull/dist/screenfull.js",
              "node_modules/hammerjs/hammer.min.js"
            ]
          },
          "configurations": {
            "production": {
              "fileReplacements": [
                {
                  "replace": "src/environments/environment.ts",
                  "with": "src/environments/environment.prod.ts"
                }
              ],
              "optimization": true,
              "outputHashing": "all",
              "sourceMap": false,
              "extractCss": true,
              "namedChunks": false,
              "aot": true,
              "extractLicenses": true,
              "vendorChunk": false,
              "buildOptimizer": true
            }
          }
        },
        "serve": {
          "builder": "@angular-devkit/build-angular:dev-server",
          "options": {
            "browserTarget": "phoenix:build"
          },
          "configurations": {
            "production": {
              "browserTarget": "phoenix:build:production"
            }
          }
        },
        "extract-i18n": {
          "builder": "@angular-devkit/build-angular:extract-i18n",
          "options": {
            "browserTarget": "phoenix:build"
          }
        },
        "test": {
          "builder": "@angular-devkit/build-angular:karma",
          "options": {
            "main": "src/test.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "src/tsconfig.spec.json",
            "karmaConfig": "src/karma.conf.js",
            "styles": [
              "src/styles.scss"
            ],
            "scripts": [],
            "assets": [
              "src/favicon.ico",
              "src/assets"
            ]
          }
        },
        "lint": {
          "builder": "@angular-devkit/build-angular:tslint",
          "options": {
            "tsConfig": [
              "src/tsconfig.app.json",
              "src/tsconfig.spec.json"
            ],
            "exclude": [
              "**/node_modules/**"
            ]
          }
        }
      }
    },
    "phoenix-e2e": {
      "root": "e2e/",
      "projectType": "application",
      "architect": {
        "e2e": {
          "builder": "@angular-devkit/build-angular:protractor",
          "options": {
            "protractorConfig": "e2e/protractor.conf.js",
            "devServerTarget": "phoenix:serve"
          },
          "configurations": {
            "production": {
              "devServerTarget": "phoenix:serve:production"
            }
          }
        },
        "lint": {
          "builder": "@angular-devkit/build-angular:tslint",
          "options": {
            "tsConfig": "e2e/tsconfig.e2e.json",
            "exclude": [
              "**/node_modules/**"
            ]
          }
        }
      }
    }
  },
  "defaultProject": "phoenix"
}

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

import { MDBBootstrapModulesPro, MDBSpinningPreloader } from 'ng-uikit-pro-standard';


import { AppComponent } from './app.component';
import { RestApiService } from './services/rest-api.service';
import { SessionInfoService } from './services/session-info.service';
import { UserService } from './services/user.service';


@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    HttpClientModule,
    MDBBootstrapModulesPro.forRoot()
  ],
  providers: [MDBSpinningPreloader, RestApiService, SessionInfoService, UserService],
  bootstrap: [AppComponent]
})
export class AppModule { }

Could you provide the code from your package.json (please remember to remove your private token if you use one), angular.json and app.module?