Premiere loads up to the home screen just fine. When I load a project with Waves R-Compressor on a couple of tracks Premiere Pro freezes at about 75% of the load. I think it has something to do with dvaaudiofilterscan and Catalina's Privacy and Security settings.
Premiere will load a project without the Waves plug ins used on any tracks, but still with Waves plug ins activated in the Premire Pro Audio Plug In Manager.
Also, if I remove the Waves plug ins from the "Audio Plug-In manager" in Premiere Pro Preferences before loading the project with Waves plug ins, it will load with the Waves plug ins indicated as "Offline (filter...)"
I've uninstalled and reinstalled Premiere Pro (with "keep settings"). I've tried adding a few things from Waves to the Mac Preferences/Security & Privacy/Accessibility list. So far, no luck.
Don't have a definitive solution but others have had past issues with dvaaudiofilterscan in MacOS Mojave and Sierra.
Search 'dvaaudiofilterscan' using the search tool at the top of this forum and see if any of the previous conversations reveal anything useful to your situation ... also I'd start with clearing your caches, and then importing your existing project into a new Premiere Pro project.