Often when I reply to a Facebook message, the message stays marked as "unread".
For instance in the screenshot below (messenger.com) the first and third conversations are OK, but the conversation in the middle is problematic: Even though the last message is by me, the person name stays bold, which I believed was supposed to indicate unread messages:
The bold/not bold status is consistent across messenger.com/fb.com/Android app.
It has been happening for years, and it is very annoying as it makes actual unread messages harder to notice.
QUESTION: Is it expected behavior, and I am misunderstanding the UI?
If this is a Facebook bug, are there known workarounds?