I've tried restarting the phone, restarted and cleared the cache as well. Problem still persists.
What does work, insofar as Gmail goes, is launching the TeslaUnread app, tapping the Gmail settings "⚙" icon, de-selecting Inbox ( turning it off ), then re-selecting it ( turning Inbox right back on again ).
Obviously this isn't a permanent solution, as no one wants to have to do that every time, but it does work in a pinch for what it's worth. Rebooting is not only
not necessary, it doesn't add anything, as someone pointed out. And if you're running Nova Launcher, neither does going to
Settings ▸ Advanced ▸ Restart Nova Launcher. The only quick solution that has worked for me is the one I describe above, which amounts to telling TeslaUnread
not to track Gmail, then telling it
to track Gmail again.
In my case the problem manifests in the opposite way of most, based on most comments I've seen ᎓ after I get a message and deal with it, the "①" badge on the Gmail icon refuses to go away, even after several minutes, and I have to get rid of it in the manner I describe.