Use the top left Autotile .. The blank one to erase things on different layers. So for that bush. Every layer that's not the bush, hit it with the top left autotile and for goodness sake don't be too impatient, this is a forum after all :blank:
Also make sure you're not holding Ctrl..
Also make sure that the impassible tile is on the greatest layer, being the 2nd or 3rd