Not sure if my question makes no sense or the case is really so complicated.
I also noticed there seem to be more problems with the unread view. On my account (and people also report this) not only the old post prior import don’t appear in unread but also most of the new ones too. I do have 5 threads in new while only one in unread at the same time. This doesn’t make sense - does it? Everything that was posted and I haven’t read yet should appear in unread unless I muted the forum. Or am I completely wrong here?