My Contacts have been refusing to sync for over a week now; the circular arrows showing the Contacts sync stay visible all the time, and the sync date/time does not update. All my other accounts are working, it's just the Google contacts. I've tried clearing various caches, removing and readding the account, downgrading Play services, reinstalling completely, nothing works. I've never had this problem before. I think it may have something to do with the Play services for Instant apps that was rolled out recently; things started getting wonky around that time. I don't know for sure. I'd rather not have to reflash over this though.