It was previously reported. I think the female form of Hippopotas and Hippowdon was not handled (it was actually form 1, and at that point I think it was programmed to only expect form 0).
The question mark appears whenever the mon in question has form ID larger than expected form ID.
Try updating PKHeX and see if that error is still there. (I'm not sure which version fixed it, if I'm being honest)
Anyway your Hippo is correct, so it's fine.
Hello, guys! How are you doing?
I have a doubt about PKHeX. When editing a pokémon's OT info, if one wants to set their own info, must they manually input this info?
Isn't there a "Load from save file" / "Trainer's own ID" button, as there was in PokeGen?
Thanks a lot in advance!