It packages fine when i remove the media_player->OpenSource() line from C++.
I had the same class implemented in blueprints in the exact same fashion and it worked flawlessly. It’s some iffyness on the C++ side.
I also manually added the Media, MediaAssets plugins in my c++ dependency modules in my .cs file and it didn’t do the trick.
Don’t have logs for you (as I couldn’t halt development for this), but that’s the behaviour I’m experiencing.
Packages fine and finds the Media plugins fine when doing things in blueprints; fails on packaging when doing things in C++.