Hi @Rob_W,
Thanks for the updated message.
Apple released Audio Unit support for iOS many years ago, which offers much more flexible options compared to Inter-App Audio. Also, Audio Unit can be seen as Apple’s successor of Inter-App Audio (which is no longer supported).
We recommend getting in touch with app vendors asking them to release AU versions of their IAA plug-ins to make them aware about the demand.
In this regard, please check our Limitations of Inter-App Audio format article:
P.S.: If you encounter an empty AU plug-in screen as show in your message, it might work to shut down and restart Cubasis and/or launching the stand alone AU app version. See the linke article above for more details.
Hope that helps.
Best,
Lars