Let me first state that I have tried to get the answer to this question from my Google account representative. After trying to get an answer for several weeks, he emailed me an
We have quite a few sites using various map packages and like 09stephenb said we simply had to wait.
Things started playing up in all versions of IE and older versions of FireFox (12.0)
Firefox 25 and Chrome were handling the wrapped maps fine.
Just as we were planning a rewrite of all scripts this morning it seems Google have sorted out the wrapped version for the problematic ones mentioned before.
Just in case anyone here has missed this and is beginning to migrate.
Cheers. Liam