Hi @shaunault,
sorry for the delayed reply. BTW, for faster support, please use wpForo Support forum: https://wpforo.com/community/
This is either cache/optimizer/minifier plugin conflict or some JS error in your website. The JS error comes from other plugins or the theme.
First please make sure wpForo forum page is excluded from your cache plugin, here is the instruction: https://wpforo.com/community/faq/wpforo-and-cache-plugins/
Then disable other plugins and check it again. Don’t forget purge all caches.