Only suggestion I have is that you send the phone for repair

Hopefully it's still under warranty ..

 

The short version of my similar issue is that you need to uncheck/stop backing your data up to Google, restart your phone and then do a factory reset. Sign in without backing data up (select no when prompted) and start totally fresh.
The long version is that my son's phone (D4) started doing that and we couldn't figure it out, he did a few factory resets and/or safe mode boots and even got a new SIM. I finally sent him a backup D4 I had that never had this issue, not once did it do that in the year plus that I used it. He activated it and it did it right away. When he came home recently I stopped backing data up, factory reset, activated w/out backing data up and the phone's been just fine since.
It's a PITA solution but, at least for him, it did work. I don't know what makes it start and why that seems to get 'stuck' on the associated Gmail/files but something got screwed up. Starting totally fresh worked. Hopefully it will for you too.

edit: It's not just Moto phones, it's not carrier specific and it's not a hardware/phone issue but it may be a Jelly Bean issue. I did a ton of Googling and it's happening to a lot of phones. Sometimes a new phone did help but not always (like my case, it's not the phone), sometimes a new SIM helped but not always, sometimes a factory reset helped but not always.