From what location are you loading those images ? Is that in your OS user directory as you may not have access to this location due to sandbox restrictions?

You can check the Web Console (Tools -> Web Developer) for messages about blocked content and about the presence of mixed or unsafe content.

• https://firefox-source-docs.mozilla.org/devtools-user/web_console/

You can check the Network Monitor to see if content is blocked or otherwise fails to load.

• https://firefox-source-docs.mozilla.org/devtools-user/network_monitor/

If necessary use "Ctrl+F5" or "Ctrl+Shift+R" (Mac: Command+Shift+R) to reload the page and bypass the cache to generate a fresh log.

I'm not sure if desktop Firefox does support this image format due to licensing issues.

Thanks for Command+Shift+R I've been clearing history and cache and opening new private window each time.

Neither Chrome nor Firefox render heics: http://wavehands.net/dancesHEIC/dancesHeic.htm

but each is happy with jpegs and pngs: https://wavehands.net/dancesJPG/dancesJPG.htm

Safari renders both ok.

cheers

Surah, I gave thumbs down because you had not looked at the tests online.

Safari with user agent Google Chrome Windows and user agent Microsoft Edge renders the heic version correctly. The problem may be limited to mac OS heics.

Cheers.