I’ve actually had great success using JamUp/JamUp Pro as IAA inserts in the latest version of Cubasis. I’m using an iPad 4 with 128GB.
I recently abandoned using Amplitube as a guitar processor plugin as it was just too bloated and consumed an excessive amount of CPU bandwidth.
I find JamUp uses about half what Amplitube does and would be even better if they released a “plug-in” app without the sampler/recorder/audio player baggage.
Occasionally I have to double-tap/swipe up JamUp and clear/reload in Cubasis, but it’s quite rare and it happens more often with other IAA plug-ins.
If you can describe your problem in more detail, maybe I can help,
cheers,
Carl642