Mail not displaying contents in Gmail folder

All of a sudden, the contents of one of my Gmail folders aren't displaying. Emails are still on the Gmail server, other Gmail accounts I have display all the folder contents, but not this one.

I've synced, rebuilt, deleted and installed. I've closed mail and restarted the computer. What's up? Is this a new issue with an update? I see the contents in their folders on my iPhone and iPad.