What makes it even harder is the fact that the updates roll out in different global regions at different times. I always seem a week behind the Americans when it comes to updates. At least that;s what I notice with the bigger OS updates. Folks talk about the big update and I see it a week later. I imagine it's all based on infrastructure and legal issues.

With the november update the "add track" dialog pops up by commands as "clear audio folder" and "insert fx chain preset" and randomly by other commands. Also it is not possible to bind any key for "insert marker". Also my Behringer X-Touch can't insert a marker since this update.
I also see no synthesizer tab.
But obviously I'm almost the only one - I see this phenomenon on all my computers. So it cannot be due to the hardware and windows updates.
Very mistery.
 

I've had the 'add track' dialogue pop up randomly when doing something else.

For me the problem started with Sonar crashing when loading projects. Loading projects in safe mode was possible when confirming each plug-in one by one. A workaround that works for me. After loading successfully Sonar was rock solid as always.
 
Rolled back to 2016.10 and still had the same issues, went back to 2016.11. Windows 10 updates are up to date.
 
Subsequent project loads mostly work without crashing SONARPLT.EXE. But the problem reoccurs after rebooting the PC.
 
Then I decided to do a plug-in reset and rescan. The rescan only gets to  CA-2A.._64.dll and hangs. Closing the box and clicking Reset again this time successfully scans CA-2A but hangs at RaptureSession_64, same repeats with about 6 more plug-ins. Then the rescan is complete. Another workaround that's ok for me so far.
 
In between I had "Runtime Error! R6025: pure virtual function call", but not reproducable.
 
I'm sharing my experience here because it may help narrow in on the problem and the workarounds may work for others as well.
 

@klauselix: I have the same problems with CA-2A and I got the same Runtime Error R6025.
 
I deinstalled CA-2A and rescaned all plugins. Now I can load my older projects, but can't use CA-2A anymore.
I tried to roll back, but as you mentioned the issues are the same.
 
A second crash was caused by melodyne 4.1 dll, when I open older projects.
 
I never had so much problems with Sonar.
I'm not sure if it's a problem of 2016.11 Sonar-update or Win 10. The last update of Win10 was on 1.12.16
 
 
 

Interesting. I'm still on Melodyne 4.0 which seems to be fine for now. Was planning to go to 4.1 this week. Will pushi this back now.

As a comparison, my Windows 10 (x64) is fully up to date and the latest Sonar Platinum update seems to be fine.
 
Since the CC update, I've installed and scanned two new Waves plugins (Super Tap / Electric 200 Piano) and worked a on an existing session which includes CA-2A.  Melodyne Editor 4.1 is also operating as expected.
 
I've posted this in the hope that it helps to eliminate possible culprits.

Songroom
As a comparison, my Windows 10 (x64) is fully up to date and the latest Sonar Platinum update seems to be fine.
 
Since the CC update, I've installed and scanned two new Waves plugins (Super Tap / Electric 200 Piano) and worked a on an existing session which includes CA-2A.  Melodyne Editor 4.1 is also operating as expected.
 
I've posted this in the hope that it helps to eliminate possible culprits.

Same here except I've installed different plugins since the update.

I have also had the crash on project open a number of times since installing the update. Similar to some of the other reports after a crash, re-opening the project does work, but it may crash once or twice more before it does.
I have not had a crash for a while prior to that. Dont know if it is related but when it does crash, the vst scanner is running during the crash and gets stuck on waves.
Also running win 10, i have delayed updates, but am connected to the net.

Just to add to the confusion, I noticed in the CCC that ehre was an update to the "Cakewalk Loopmasters Content Collection"
 
I have tried to update it several times but keep on getting this message:
 

 
Does anyone have a clue what this means or how to fix it?
 
 
Cheers.