I think that solution proposed by andyg65 is most applicable here. I've faced this issue multiple times when using mods altering npc animations. If you use more than 1 mod altering your npc animations based on some variables, it can result in a conflict at some point and interaction with your follower may get crashed. Generally if you do not use Bash for more sophisticated solutions for collisions between mods just play with this MCM animations or try teleport somehow the follower. The problem is if you use standard follower; many custom ones offers teleports spells or just use AFT, however in my case it was in conflict with another mods :D.