Hope I'm not too late - I've only just seen this thread.
A few things that cannot be fixed easily by our patchmakers are:
1: the "end of day bug" reverting back 2 sessions. This is recoverable by us by saving before the expected close and reverting back if the problem occurs. An extension of this however, is that a drawn test match can try and go into day 6, which causes the game to crash. I cannot find a fix for this (as The_gas will testify to)
2: The new ball not being received in a test match.
3: Bowlers bowling more than 10 overs in ODI.
There are other things that are annoying, but I think these are 3 fundamental issues that hopefully could be fixed quite easily.
Edit: I play on pc, but I believe many people have complained about not being able to save a game during a test match on the x-box.