Hi @doobeedoo welcome to the forum. If you have not already, it is advisable to perform a clean install using the latest installer via the steps at the top of the following forum page:
https://forum.scalermusic.com/t/scaler-3-update-crash-files/20472
If you have already done so and this issue persists, would you mind explaining a bit further what is happening? Are the sounds selectable via the sounds browser and simply make no sound when played? Or are they not listed in the sounds browser at all?
Perhaps you could post a screenshot of your sounds browser in case it doesn’t look right for any reason. Regardless it sounds like you’re saying you can load a 3rd party instrument plugin via Scaler 3’s sounds browser and this plays without issue. Is that correct?