Issue: marked forums read, then somehow they were unmarked read

[Moltres Rider]

I have marked several forums read, and it showed that there was no unread topics, I come back 5 minutes later, nothing has changed, but the forums were unmarked read, for example 'Pokemon General' after I was the last person to post, I marked the forum read, and it showed no new posts come back 5 minutes later, I still am the last to post but there claims to be new posts but there isn't somehow it unmarked itself read, making it unread