Rush stuck at "Preparing Media" step

I'm having the same problem as described here: https://community.adobe.com/t5/premiere-rush/rush-got-stuck-at-preparing-media-mac/m-p/10605661

When I open Premiere Rush on a fresh install, when I select media (either my own or when following the tutorial and using the sample media) and click "Create", the app immediately hangs on the "Preparing Media" screen. No progress appears on the progress bar. When I click "Cancel", the progress bar jumps to 100% but nothing else changes, and I have to force-quit the app.

Then if I try to reopen the app, it just hangs on the loading screen. The only way to get out of that is to:

1. Close Rush
2. Log out of Creative Cloud
3. Delete the contents of ~/Documents/Adobe/
4. Log back in to Creative Cloud
5. Re-open Rush
6. Now I'm back at the original issue, where creating a project just hangs on "Preparing media"

13" MacBook Pro, 2.4 GHz dual core i7, 16 GB RAM, Intel Iris Graphics 540 1536 MB. macOS Big Sur 11.2.3.

How can I get around this and start being able to use Rush? Thanks!