The 'threads' view for me is empty ('Tend to your threads') but is always bold in the sidebar, has "1 new reply" and shows up with "more unreads ^" arrow when I scroll past it

Which platform are you on @spacemods?

Windows, in-browser Firefox

I think I was mentioned by name but that thread is out of free messages range

Maybe you can click the @ mentions icon top right to view the message? (and hopefully clear the alert)

I've never seen that happen in the browser. I have seen it happen in the Windows desktop client (ghost "unread" messages that just won't go away)

Hmm, it shows yours just now but not the past one

Try SHIFT+ESC and you'll mark everything as read 😉

It marks everything else as read, but not that one - good to know, though! I've put in a slack support ticket, I'll see what they say