Sorry, this is an oldish post, I haven't been here in a while.
This is a feature not a bug.
The text always floats to the top in plan view so it can remain readable. If you don't need it to be readable perhaps you should switch it off. If you do need it to be readable then it is working fine. You might want to consider switching it off anyway, and putting in your own room tags, so you can relocate them to a position where they dont clash with the plant.