MotoX Address Book Won't Sync Over WiFi?

[Father Tech]

I have the MotoX on AT&T. My phone's address book ("People") won't sync with AT&T's online address book over WiFi. When I turn my phone's WiFi connection off, I can sync my address book. When I turn my phone's WiFi connection on, I can't sync. I tried this several times.

Has anyone else experienced this problem? I can sync over the mobile data connection, but not over WiFi?

 

[Father Tech]

AT&T Support created a ticket for this issue.