Plex hangs at splash screen (Fresh install Debian 8)

I’ve just set up a server running Debian 8 and when I try to access Plex through my.ip:32400/web I get the splash screen, but no further (no login prompt, etc). I have claimed the server through an SSH tunnel already and can access the settings from there, which say the server is accessible remotely. Plex was set up using this script:

I don’t want to reinstall with Ubuntu since I’ve already spent all day setting up webvirtmgr and the letsencrypt SSL certificate following a guide on this forum. I set it to force ssl by redirecting http to ssl. I’m curious if the SSL certificate has something to do with this - I do get an SSL error when I access Plex, the certificate causing the error is a Plex certificate. Trusting the certificate does nothing.

EDIT: Actually this seems to be an Opera issue. I use Opera browser and just realized that I can access plex normally from Chrome or Safari. But from Opera, I can only access Plex through an SSH tunnel. Preeettty weird.