protontricks not working, both pre-installed and flatpak versions

I'm trying to run protontricks, but it fails to open any prefixes. No matter which prefix I choose, no matter whether I use the pre-installed protontricks 1.11.1 or the flatpak 1.15.8, I get the Invalid file magic number error. Not sure how to debug since I have no idea how to drop into a debugger to get more useful info about the error...