Is there any list of all the bugs that are fixed in Platinum since X3?
I am especially curious to know if step sequencer clips are going to be more stable - because in X3, after enough edits, something in the midi becomes corrupted and some notes don't play anymore.
I did not see any list of known solved issues in the "What's new".

Not yet. You may recall the bug fix list for X3 was published a few days after the release of X3 along with with the first patch.

CadErik
Is there any list of all the bugs that are fixed in Platinum since X3?
I am especially curious to know if step sequencer clips are going to be more stable - because in X3, after enough edits, something in the midi becomes corrupted and some notes don't play anymore.
I did not see any list of known solved issues in the "What's new".

You probably know this, but did you increase the MIDI buffer size? That seems to be the #1 cause of MIDI notes not playing past a certain point. More details in this thread.

If no other options exist - you could also try bouncing to midi, and see if that made things playback properly.
 
Bob Bone
 

I can confirm that NO list of bug fixes comes with the pre release Soanr Platinum which I've been running for about 4 hours now.