When using the leash on an entity such as a horse in survivals attaches fine but the leash then floats away from the player and as such are unable to place "tie" the leash to a fence post.

To fix this in game requires two leash items to be in the inventory although only one is ever used.

Image file name Leash shows the bug, image file name Leash 2 shows the leash behaving normally when 2 leashes are in the inventory

Creative is not affected by this bug.