I have noticed the same problem today for the first time.
I have 66 photos opened / loaded into Photo AI 2.2.1 on Win10, some with just Autopilot settings, some with modified settings.
I can not export any photo, regardless of target filepath and target file format.
The export always starts (“processing”), but never saves the first file and freezes there. I can cancel the processing and resume or restart, but it never makes it to saving the first file.
Funnily enough, I can save photos that were edited using the “Remove BETA” function. No luck when this feature was not used, though.