XF 2.1 "Go to first unread" at the top of a thread will not take one member to any posts that are older than 30 days

[Stuart Wright]

I have a member whose oldest posts when navigating to first unread is never more than 30 days old.
Other members do not have this issue.
Any idea what the cause could be?
Thanks

 

[Mike]

This is related to the "Read marking data lifetime" option. Anything older than that is automatically considered to be read. Even if you've never read anything in a thread, clicking that link will jump you to the first post after that time.

(If we have no knowledge of whether you've read a thread, we hedge our bets and take you to the beginning of the thread. It's possible you may have read it but the data has been cleaned up, so that link roughly helps to jump you to a more recent point.)

 

[Stuart Wright]

Thanks @Mike. 30 days by default. So for people who use the forums less often, it needs to be longer? Will increasing it to, say 2 or 3 months have a significant impact on performance? I'm guessing not.