Persistent Unread Message indicator

[taoeffect]

Problem

For some reason in the GIG group it's showing the #general chatroom as having an unread message for me:

This is also causing a red bad to appear on the group icon in the tab menu (favicon) and in the app too:

It won't go away, even if I switch from #general to another chatroom and back and scroll all the way down.

Solution

Find out why this is happening and fix.

[taoeffect]

FYI, the unread indicator went away after I posted a new message to the #general channel.