You're right. There is some issues going on with the primal app. I did some testing.

I removed all the relays and added 2 relays. Then I made a post. When I checked the post it was pushed by the nostr band relay and that relay was not part of the 2 relays I added.

I didn't run into any media issues. I seems the default media upload server is blossom.primal.net

I don't understand much about the media servers since I host my own media.