The forum seems to have issues with ajax loading, it keeps loading incomplete without layout. Doing a manual refresh on the same page seems to fix it but you cant expect a user to know that, this is unintended behavior, any tips to fix?
I'm sorry, but I don't follow you. Could you please clarify a bit?
Please deactivate the W3 Total Cache plugin and check it again. If it works just exclude forum page from plugin settings.
Please do yourself a favor and uninstall W3TC. There are a lot of really good caching plugins if you need one. W3TC is only trouble and huge load for your site.
Also in wpForo pages, you are still (i think) using W3TC Minified using disk as i see in the html code.
Finally exclude wpforo pages from Yoast SEO. Right now you have both (Yoast AND wpForo SEO).
About your problem: it could be a theme or some plugin conflict. How to solve it ? I'm afraid the hard way, switch to the default theme and check if the problem is gone. If not, enable your theme and disable your plugins one by one to see what the conflict is.
Also you could enable WP Debug to a LOG and check for errors, sometimes it gives hints about a problem.
About the caching: what web server are you on (i can't see since you use CF) ?