I’d like to start by asking what else has changed on your site? You may notice that none of the buttons and actions on the forum do anything – they do not even produce errors! In fact the script console does not appear to even notice that the page is being loaded every time which is most odd.

I do see that you are using wp-super-cache – is that a recent addition? You can not cache the foru8m page so you will need to work through the wp-super-cache option to exclude the forum slug which – with super-cache is on the Advanced admin panel. Perhaps you should do that first – CLEAR out ALL cached pages, re-update the forum permalinks and then come back if things are still not right with the answer to my question above…

wp-super-cache was deactivated – but not deleted, which it is now and that solved the problem.

I have not used wp-super-cache for the past couple of Weeks – it appears you hit the root-cause for the problem spot-on, so I’ll carry-on to check functionality is OK throughout the forum.

Wow- wasn’t necessarily sure it would fix the lot but hey – let’s hope that’s all it was.

To fully remove wp-super-cache you need to remove the entire set of cached files, the code files from the wp-content folder AND the added .htaccess rules.