Delve map resetting on same character.

Started doing a bit of delving and twice now I have gone to a new node where the circle of light on the ground to start the delve segment is there but does not do anything when running over it, the cart just sits there and does nothing.

So I will port back to the encampment and select open the map to select the node again and the map has regenerated a new map as if i was starting delve on another character, with the middle direct down mine shaft at the furthest depth i had been to previously, with all new nodes around and my progress lost.