So, did the core-version do any good?
It's rather seldom on mine; but when it happens, a reset is usually needed - though sometimes holding "backspace"
may clear the buffer. I'm always using my MiST in the "Viking-mode", so I don't know, if it's mode-dependant.
I really can't recall, if there was a patch for this problem. It's been years since I used any of my real Ataris.
Unfortunately the MiST is rather little compatible, less than half of my programs, which do work on STeem,
run on the MiST!
Cubase, (Mega)ST(e)(fm), TT, Falcon, Jaguar, MiST.