Hmm as if by magic this doesn't freeze anymore.
All I did was add some debugging to the functions and it worked. Took the debug out - still works.
I had something similar and rare in delphi where the alignment of code in memory was sometimes wrong and changing something (anything) recompiled that section differently. Anyway, happy that it's working, not so happy to not know.
Another thing that was hapenning was that a certain part of the game worked at 30fps and just by clearing the player cache (thanks AL) this section returned to 60fps again.
I guess the same things are related, but the button hang on 4.x was also from a standalone apk build.
Still scratching head..