Yes this is actually an issue for few classes using stance. Running = out of fight = cancel stance and back to normal skills. This can happens in few instances, not only in Nayul unfortunatly.
Moreover, you need to know that sssassin is one of the most bugged class in bns, with the blade dancer
I let you discover multiple others bugs on assassin, like not being able to use "Shadow dash" when it's availible, in the back of few bosses, and breaking a part of your rotation.