I was working on a project and everything was fine until I had to duplicate some comps. Those comps had other comps inside as well. After Effects stop reading the track mattes in thos comps and stopped reading the layers as well. Turning on and off layers or purging the memory, the layers were still present on the page.
At one point, AE stopped recognizing a 4k png I had. It went black and then became a small white square in the comp. Eventually AE crashed and I got an error message.
To get around the problem, I had to import the file into a new project and slowly work through comps. In the new file, AE had disconnected my track mattes as well, so I have to go through mose of my comps and reattach the track mattes.
This was an absolute nightmare.
Import and export