The same thing for me. "insert coin button is not working" Mame games are impossible to play even using key "5" of my keyboard.
I thought with 13.07.18 update that issue was solved but nothing.
One last thing : i don't think you need a seperate coin slot for P2. Such games are quite seldom, and mostly for games were both players play simultaneously
I'm glad I could help you 🙂 This is what the forum is for 🙂
