I'm already encountering a dozen threads which are looping me back to homepage if I try to access them via their title, Lol. I know how to fix it for myself but it can be dependent on what PPP is chosen. US Politics was working fine for me but was broken for CGI when he tried to access it via its title.
Reason is because a comment next in line for him to view was deleted, for example, if he was on 10 PPP and the 4th post in that line was deleted, it will loop him back to the homepage if he tried to access the thread through the title - Clicking the title automatically takes to you your last point of viewing as you're all aware.
The easy way to fix it if anyone is unaware is by clicking directly on Page 1 and then skipping straight to the last page, in effect skipping over those comments, or clicking directly on the last page if that is possible. In effect it will update your view progress to the end so the deleted comment which was blocking you from accessing the thread should no longer be a problem.
Think there may be issues if there's a comment which was deleted within the range of your PPP though. In that case, unfortunately the only thing you can do is wait for whatever amount of new comments to be made in the thread matches to your PPP - 10 PPP = 10 New Comments.
Super Official Anime Discussion Thread - Summer 2019!
Is this working okay? Try to access it in multiple ways.
When I click it it goes to page 1.
Maybe the solution here is, clear the records of all the last post seen for each thread for each user. That way when they click the title it will just take them to the first page. Then going forward let the database record their last position.