Same on Steam PC when completing game in Veteran. I tried reflying a mission I had accidentally finished on Ace thinking having the one done on a different difficulty was causing the issue. The medals I earned on that run (but not the previous one) showed up after finishing the mission, then disappeared again after playing a fleet battle match.
All my medals are gone too. I had completed the game on Ace only to find it didn't count, so I went back and beat 8 of the earlier missions again on Ace, with medals appearing in 13/14 missions. Upon reopening the game, all my medals are gone.
I've just finished story mode on highest level of difficulty and... i didn't get any trophy and game lost every my medal from missions 1-5. I finished story mode second time, first time i didn't get any trophy too, but i thought that it happened because i changed level of difficulty on higher during it... This game is a joke. I am trophy hunter - just give me back my trophies or money. Natahriel from ps4.
Best solution, redo the game on story mode, only playing campaign you'll keep all medals off you don't switch modes
