Thanks for your message.
The use of Inter-App Audio in particular, and Audio Unit can come with some limitations and issues, given the format and/or the instruments and effects app in use. These issues are mostly unrelated to Cubasis, and are valid for other DAW type apps too.
Please have a look at our dedicated forum articles, to learn more:
Limitations of Inter-App Audio
Limitations of Audio Unit extensions
Please let us have more information, what third party instruments and effects apps you have in use.
Furthermore please check, if the problem is solved, when not using some of these apps.
If this is the case, we’d recommend to get in touch with them to let them know about the problem.
Hope that helps!