Dear @geoffrey.seynhaeve 

This problem is caused by overflow: hidden on .sb-item.body class. This style hides all content which would overflow the accordion item height.

Unfortunately, for now, I can't provide you ready-to-use answer, because we have to resolve this problem in our code.

As a workaround, I would advise you to set overflow: unset !important on .sb-item-body class.

This will break a little of accordion animation, but your select will be visible.

Please try to add the below code into your styles.scss stylesheet:

.sb-item-body {
  overflow: unset !important;
}

Best Regards,

Damian