Getting false notifications from mail
iPhone 6s. This happened when I applied 11.3
Basically, mail repeatedly shows me that I have three new messages in a gmail inbox. If I go to the inbox, eventually it'll confirm that they don't exist, but randomly again later I'll get the little "3" on the mail icon, and it'll be the same thing. It thinks I have new messages, but I don't.
Obviously, no false notifications are showing up on my desktop or my iPad. But for some reason, the iPhone keeps thinking I've got three new gmail emails when I don't.
I tried restarting the device. I tried deactivating the gmail email, force-quitting the mail app, and then re-activating the gmail email ... first thing, it tells me I've got those three new messages again. (I haven't completely deleted the gmail account yet, just deactivated it.)
Any other ideas about how to fix this?
iPhone 6s, iOS 11.3