Broken CSS inspector on some site

When I try to view the styles of elements on the site https://priem.mirea.ru/lk/ in the inspector, Firefox writes that no one element is selected. Running safe mode (without add-ons) from about:support does nothing.

What could be the reason for this behavior? This happens only on this site; I haven’t encountered this anywhere else.

Unfortunately the website doesn’t seem to load for me, is it still up?

Do you see any error in the Browser Console? (https://firefox-source-docs.mozilla.org/devtools-user/browser_console/index.html)

Yes, the site is working.

I recorded the demo video in a new Firefox profile with disabled “Enhanced Tracking Protection”. After loading the site there are no errors in the console. When I select any element, Firefox writes “No element selected” in the CSS editor.

https://drive.google.com/drive/folders/1Pzqaj4D5wYD2QPrDtC9NJ73s9oFRAjfO

I can’t access the website, maybe it’s geoblocked or something? (I’m in France)

Thanks for the video, it shows that the problem shows on all the nodes. I wonder if we have some kind of pending task we’re waiting for, like a document would be loading for ever. Do you know if this websites uses document.write or anything that might be unusual?

Also, I think we were misunderstood, I was asking logs from the Browser Console (https://firefox-source-docs.mozilla.org/devtools-user/browser_console/index.html), not the regular web console. The Browser Console would have warning and errors for Firefox itself, not the content page, and that could be helpful here