In my experience, Premiere Pro 2021 does not open MOGRTs exported from After Effects 2022. Consternation ensued! Until I realized there was that version gap between the two. I discovered that fact when I I tried importing to Pr from the desktop rather than the Library and was finally greeted with the compatibility message.

Switching over to Pr 2022 worked as expected, with successful imports of Ae 2022 MOGRTs.