1. Tried but no Changes. I still shows blank
2. Sorry, but don't know how to do that
3. Here is the message link which is not getting edited and all similar posts with equal length are behaving the same
I have raised the ticket. Actually its very wierd. When I am creating another thread of similar length, I am too able to create and edit but unable to EDIT these old important lists which got upgraded from XF 1.1.5
This looks like it might be dependent on PCRE settings - I think one of the regexes was backtracking too much. It likely only comes up with posts from 1.1 or before that were heavily formatted in the WYSIWYG editor.
Regardless, changing library/XenForo/BbCode/Formatter/Wysiwyg.php fixes it. Replace: