Limitations of Inter-App Audio

Aloha, LSlowak; I’ve been a Cubaser since '04.
Now on newest iPad Pro, 128gb, nearly empty, so plenty of room.
Drum Loops HD > Audiobus > Cubasis2; all 3 apps updated to most recent V’s.
I’ve searched for my exact issue, no find.
My issue; Audiobus tracking into Cubasis2 just fine for 4 tracks.
Then, Drum Loops HD gives 0 signal. Dead stick.
Trashed & deleted all I could.
I looked into Drum Loops HD – iOS Apps For Musicians
The app producer of DL-HD & DL-HD2; that’s the link to their instructions on using
AudioCopy app to take their copy their sample up & paste it into the Cubasis2 Media list.
On selecting ‘import’, & then the ‘AudioCopy’ option, Cubasis2 freezes to a white screen,
that says “Failed to connect to AudioCopy. Please try again!”
And the blue link at bottom of page, “Done”, does not respond.
Cubasis2 is froze there. I’ve tried all combinations I can think of.
What I think is most odd, is Cubasis did fine on 4 tracks, bits & pieces, mostly,
& then simply refused to comply anymore than that.
And the cease of audio playback of any sort out of DL-HD, lost at the same time as Cubasis2 quit working?
Strange, CPU load was barely marked all the way through.
Any advise on this, please? Thank you.