These hanging issues sure do remind me of prior threads where BitBridge or JBridge is unable to clear memory, and Sonar hangs as a result of some resource not releasing.
BitBridge and JBridge are 2 bridging programs that make it possible for 32-bit plugins to be used in 64-bit Sonar. BitBridge is freely included with Sonar, and JBridge is a commercial program that performs a similar function.
Many many folks have moved to try to completely eliminate the use of 32-bit 3rd-party plugins in a 64-bit Sonar installation, or at least reduce their use to as few as possible - for precisely these kinds of reasons.
A lot of the larger software companies recognized the issues that can arise with mixing 32-bit plugins in a 64-bit host program, such as Sonar, and many of them have invested time and effort into upgrading those plugins to 64-bit - most of the time as a free update.
If you look in Task Manager, and see either BitBridge or JBridge running, then you know that at least one of your loaded plugins in a project is 32-bit, and potentially can cause Sonar to hang or crash, sometimes also followed by an inability to cancel and restart Sonar.
The very few 32-bit plugins I still have are in a separate plugin folder, and only those that I have repeatedly tested and found to be stable are ever placed into that folder, and then that folder is included in the VST search paths in Sonar's plugin manager.
I hope some of the above is of use to you. I would also offer that once I moved to almost completely using only 64-bit plugins (all new projects are only using 64-bit plugins now for me), Sonar instantly became tons more stable.
Bob Bone