Do you see any failing requests in browser’s developer tools > network tab? Or any errors in console?
Do you face the issue also while in Incognito mode? If not, maybe some of Firefox extensions (e.g. some dark mode extensions or custom css injectors) are the root cause of issue.
I think you’ve got me closer:
Using an incognito window does not have any problems. So, I disabled all my extensions, cleared all cache, cookies, and history (on a regular window). Then, I logged in again (on a regular window) and I still have the same problem.
There is a developer console error:
Exact same problem and symptoms here: Firefox, images not loading, shift-reload making them work until tab close, CORS error messages but no change when I disable CORS with a extension, same NS_ERROR in the network tab.
Yes, it works in private mode (I guess because private mode bypass the cache, or it wouldn’t be private). And it never worked, even before I set-up any dashboards or installed any add-on (I’ve only been using HA for about a month, so I remember).
But it also works in Firefox Portable (which use a new separate profile from Firefox normal, so no extensions). Even when closing FF portable and reopening, so with using the cache of the previous session. It’s probably caused by some Firefox extensions, of which I have unfortunately plenty
I disabled my user agent switcher extension, and suddenly it worked. Better yet, I re-enabled it after, and it still works! I have all the icons displayed now
Yeah, I feel like there should be a copy of these icons available in Home Assistant. Maybe it’s easier to be network hosted, but wouldn’t that also mess with the appearance of Home Assistant for those who have their instance completely “air-gapped.”
EDIT: Have read the previous discussion relating to this topic and understand that downloading all the icons would require a large size increase. Instead, why not allow the user to choose with an option in Home Assistant? Allow the user to download all icons, only the ones in use, or not download any.