@pulsewalk
The problems you are experiencing were similar to the ones I experienced on my project. I'm inclined to agree that it is probably project related. In my case my project has only forty two tracks. I too have gone down similar roots as yourself to try to resolve the problem. I will send a .cwp file of my project to the developers to see if we can get to the bottom of this. FWIW the project I'm working on is four years old, pre-pandemic, and was put on hold because of the pandemic. I have since transferred all of the project over to Reaper and I am finishing the project there. I opened a couple of other projects from the same era in CbB and they opened and played back fine but in both of these I had not frozen/unfroze any of the tracks.