I still see some kind of optimizer enabled.
And there are still JS errors. And some stray "" ( a service worker) in your root that cant be found or something.
No sure why that file does and why it in your root. Anyway that is beyond wpForo plugin.
I gave up fixing it in the end. once a user logs in, stay logged in a life time, maybe it's not that bad. haha.
I registered to your site, and loggout without a single problem.
But you have to enable verification of emails, since anybody can sign in and spam right now.