Larian Studios Forums Divinity: Original Sin 2 Divinity - Original Sin 2 - Bugs & Technical Problems Skills disappearing from bar

I had the same problem. I could leave and rejoin to get them to reappear.

This is a big issue with Incarnate Summons too. When I summon an incarnate and buff it with infusions it will often have no abilities on its bar until I leave and rejoin the game, and with them you can't open a spellbook to put them back on.