So I'm in the same boat here with no resolution so far. Here is the order of what I've experienced.
1. Downloaded on Iphone 6+; played to around level 10.
2. Logged into gamecenter
3. Downloaded on Ipad Air; played just to end of tutorial then clicked login into gamecenter, but it did not connect with my further progressed iphone game.
4. Deleted app from ipad; including deleting game center data when asked.
5. Played game on Iphone to reload game center progress. All good there.
6. Went back to ipad; downloaded app again, played through tutorial, logged into game center... and it loaded the PREVIOUS ipad progress that is said was deleted... NOT the iphone progress that is further along and supposedly the only progress that should be left after I "deleted it and its game center progress" from the ipad.
I'm so confused. I would really like to play this game on my ipad, but I cant get it to load my main progress file from my Iphone. Please help.
However if I can't get this fixed AND they don't fix the ridiculous trade center HQ situation, I may just bail on it all together.