XF 2.2 Members cannot view threads

There has been reporting of an issue of being unable to view threads.

I've suggested that they may have been added to an ignore list or they are ignoring the thread starter, but in these cases, this did not apply.

Should I rebuild the cache or do a file check?
What message/error do they receive when they attempt to view the thread?

Or does it just not appear in the thread list?
Actually both, some mentioned threads disappeared from their bookmarks and discovered that they had added people to the ignore list but don’t recall doing it and others got a ‘Oops! We ran into some problems. The requested thread could not be found.’

Here’s the thread where users are posting the issue