Hi,
There probably is one message on the mail server in the Inbox and it's unread.
Please check your web mail (web site) to see if it's really there.
If it is, but not visible in Aqua - please try Menu (three dots icon) -> Restore hidden.
If that still doesn't help, we can diagnose this further, but would need you to capture the issue in the app's other debug log (if you'd be
interested).