I just recently installed NodeBB on an Ubuntu 18.04 VPS.
My configuration is below,
Here is what I'm seeing,
I was originally running the site with Nginx and a reverse proxy, but after having these issues I stopped Nginx and updated the configuration to try and see if Nginx was the issue.
When I use Ctrl-F5 (or just F5) to reload the page everything shows up as working properly, but when I use the navbar to navigate the website I experience the issue you see above. Using inspect element the style tags appear to be empty. Also, when I log into my account the pages show as completely empty.
I've never experienced this issue before. I'm wondering if this is a filesystem permission issue. At this point I don't know what to do.