Trigger freeze?

Ampersand

I just had a bizarre freeze during Greg’s turn.

My Claustrophobia was on the board, Greg used his 3rd to create his Urza token, which was disabled by claustrophobia. Then Greg casts Ol Gnawbone, which moves into the first slot & becomes disabled. Then the freeze occurs before any other cards can be cast from his hand or anything else can trigger.

Maybe this is related to a creature with an ETB ability being disabled and it’s effect not triggering?