I created a new project and went away (to another app) for a bit. When I returned to SE, I got the "not responding" indication. I waited several minutes and force closed it. When I reopened, all of my color settings were set back to default, although my Window tabs were unchanged. I uninstalled and re-installed to get back to my original settings. I noticed that on the status line, there was an indication of an error accessing a file (probably one it was tagging). I went to the file and opened it with another editor and there was nothing wrong.
After the reinstall, I created the same project again. It looked like it was saying that ALL the files were causing errors (or at least a good number of them). I didn't see any being processed that did not have an error. Then it said Tagging (12460 remaining) and froze there. I closed it (Windows forced it).
I then created the same project in SE 20.0.3.0 and it worked fine.
The project is about 15,000 files (C and other types) and is located on a Virtual Box virtual drive partitioned on my local Solid State Drive.