Lost Progress between devices SimCity Build It

I had the same thing happen at level 34, but was able to get it fixed. I had to first contact support, and after a few emails they finally submitted it to their "experts". The "experts" then manually restored the city using their server.

So your only solution is to contact technical support, let them know you did all the troubleshooting and it still doesn't work, and ask them to submit it to an expert.

It's a hassle, but they can fix it!