In my most recent project, I started adding several melodyne region fx clips with the full melodyne version which I use within Sonar.
Without any region fx, all save operations work perfectly but with a couple of region fx, Sonar freezes from time to time when it needs to save the project.
 
Any suggestions?
(I have the latest melodyne 2.1.2 from the most recent Sonar update)

Try bouncing your Melodyned clips to track once you're happy with your edits.  To be on the safe side, clone a copy of the original track and hide it with track manager.  You should be able to save after this.

Lynn
Try bouncing your Melodyned clips to track once you're happy with your edits.  To be on the safe side, clone a copy of the original track and hide it with track manager.  You should be able to save after this.

Definitely going to bounce them... also sometimes the melodyne clips do not play anymore...

So you have seen the same bugs?

I have not used Melodyne in Platinum (yet), but in X3 Melodyne changes were actually saved within the cwp itself (if still active). There may be something going on with that part of things. Two things I try never to leave active are Region FX and AudioSnap adjustments.
 
With Melodyne, I have found it best to do surgical edits and bounce when finished (you can always edit material again if desired). Any time you bounce, SONAR replaces the wav file beneath a clip but does not delete the original (that will remain in your project/audio folder unless you manually delete it).