Negative PM count

www.byyourcommand.net/cylonforum

I noticed today that I had "Private messages [-1]"
– I had zero unread PMs.

How can I have negative PMs? So....
I had a user send me a test PM... status changed to "Private messages [0]"
– but I really had 1 unread PM

I had the same user send me a second test PM... status changed to ""Private messages [1]"
– but I really had 2 unread PMs

Attached is a capture of the out of sync 2 notices (the test PMs) ... and the 1 PM.

Also attached are the extensions I'm running (capture). Nothing new... or non phpbb approved.

I'm thinking this might be a phpbb or maybe extension bug?
...but there is always hosting nonsense...

Thank you for your time in looking this over. Searched the phpbb community forum and couldn't find anything about negative PM counts.