I understand what you mean.
But imported images are shown normaly in Phocagallery, they have thumbnails, I can click on them and see them, they are published, all is normal. In backend, I can't see any difference between an imported image.category and a new one.

I managed to have one or two imported categories that are now working. But I don't know / remember what I may have done to get them working. Gaaasp

Thank you
Patrice