After having the same question and testing how to solve, I tried using “spawn actor” just for my AI Pawns. And it worked also. So, my solution ist, just not using “spawn AI from class”, but using “spawn actor” to spawn my AI. For now, I see no bugs occurring using “spawn actor” instead “spawn AI from class”. And advantage of “spawn actor” your have all properties of the AI actor/pawn you set to “Expose on Spawn” right available.
Hope that helps next one who is facing this problem.
As side note: For me it is a bug and Epic should fix it and make “Expose on Spawn” properties of course also available for “spawn AI from class”.