For the past couple of weeks, every so often (every few days perhaps) I get this popup, from 'nowhere', ie, I don't have the App Store app open. I normally see it after I've been away for a while, or overnight it greets me as I wake the screen, so I've never seen or initiated any event myself that could cause it.
Presumably this is an auto-update of something, but it doesn't say what. It's also not a general issue, other apps seem to be auto-updating as & when they like.
Any suggestions as to how to track it down?
I'm signed in correctly. (Messages & Facetime are also absolutely fine.) Other apps update correctly, including one just today. If I go to the Store menu > View my account it goes straight to it, no issues, no further sign in required.
As far as I'm aware I have no apps on this Mac that were purchased by any other account.
Mojave 10.14.6 on an old Mac Pro 5,1 (last available macOS for this model without needing dosdude)