I get it. if you are browsing on phone, you must scroll down in your PM box to find the following categories:
Inbox
Mentions
Post Replies
Comment Replies
That's were all the replies to you are stored. They don't disappear by themselves unless you manually delete them.
it just how PMs work, as simple as that.... it doesnt go away till you hit mark as read
PMs aren't comments, they don't need to have a 'read' value stored for each and every poal account.
(post is archived)