I don't see why it wouldn't, the frame reference is still valid in 5.0.5.
Did you try
Code:
/run TargetFrame.nameBackground:Hide()
from the command-line?
Does it hide it?
If yes there's another problem with the addon (maybe it never gets to that part?)
Edit:
Or maybe the frame you need to hide is no longer that one (I've no idea what part of the targetframe that is :P)