Missing Navmesh and a npc present place?


I was testing my new mod and when I reached the top of my issgard city castle , I dismounted from horse and it ctd to desktop ... could this be related to the horse not having a navmesh underfeet or something alike? or what else could be?

CTD is usually caused by one mod deleting a vanilla object (such as navmesh) and then another mod trying to edit the same object.