WoW Armory not showing parts of website in Firefox Developer

Hello, I have problem displaying character armory web pages correctly,
Talents do not display at all, no text, no icons.

Problem occurs in Firefox Developer Edition (yes, i tried disabling all addons, themes, protection settings etc.).
Problem does not occur in Microsoft Edge.
Happens on all characters I inspect, also Item tooltips do not show at all.

Example image:

Edit: Doesn’t work for other tabs like Achievements, Collections etc., see below