I'm updating Sonar to the latest release to see if that helps. Looks like a new release is out today.

To gswitz - afraid Kingston didn't help me.
Overloud replied, they can't reproduce it, and ask if I can send a file to them where the fault occurs.
 
My reply - I'll have to do that much later today (I'm at work at the moment, in UK).  I did it with any file with TH3, including a brand new file with one midi (unused) and three audio tracks - no clips, just TH3 in each of them, no other content in the file.

Yeah, it's freezing up for me a lot too in Sonar. It's not creating minidump files for the VST though.
 
I'm thinking there's a Sonar issue at play. I've just upgraded to Kingston... let's see....

I upgraded to Kingston.

I just can't use TH3 at all. Sonar Freezes constantly.
 
If I save a project and try to re-open it, I get constant crashes.
 
Sonar Freezes. Nothing in minidump folder.
 
It just isn't usable for me. I can't open the VST after saving the project.

I tried to install TH3 on my laptop to isolate it as a computer issue and got an error trying to authorize (Internal Error) or something. Idk.
 
So ... It's not working well.
 
I think I'll just shelve it for a while.
 

Hello, it's Overloud here speaking.
Just a quick word to inform all of you having this kind of issue that we are currently working on it.
To speed things up, we may not answer immediately to every support request we receive by email or through the website, but you please be sure that the contribution of all of you has been heard and properly taken into account.
Thank you all for your reports and your patience.
 

Thanks for your reply Overloud. 
Just an update:  I tried loading TH3 on just an empty audio track, with nothing else loaded in the project.
And I still get the same results:  I close the file, reopen it. Sonar reports audio engine has stopped, I will restart the audio engine.  Press play, then stop.  Then Sonar freezes.
Thanks again, looking forward to the fix, as I really like the new version (except for the bug, of course) :)

Verified...same result...crash and burn...

Ditto.  Sigh.  Interesting, though, that it works fine IF I turn off the TH3 plugin in each track that i have it loaded on and then save it the project.  When I reopen the file, I play a few bars with TH2 turned on, which was the orignal amp sim on these tracks.  Then, I turn off TH2 and turn TH3 back on.  Bingo, it's all fine.  At least I can get into a session and it works fine after that goofy workaround.  

That's a good work around for now...just turn them off before you save and close the
session.  That might do the trick till this is fixed...