I’ve noticed that as well, inter-app instruments sometimes go ‘dark’.
It’s not so bad that we can just switch projects to get them back, but this also suggests there’s some kind of refresh going on that Steinberg could maybe easily fix.
I must also say though that I always close every apps and restart iPad before starting a session with Cubasis, by browsing the web and using other apps at the same time as Cubasis you might be seriously affecting its performance.