Does not work on Firefox and IE

It should work in all three browsers.

I’d check that javascript and cookies are enabled. Otherwise, the browsers may be out of date. Third thing to check is for javascript errors in the page.

My Firefox is up-to-date. This plugin works only on Chrome. For example, check it out: https://www.bitnet.gr/blog/ – no need to speak the language just select any post.

cmagnet, it looks like your comments are locked down to WP logged in users only.

Yeah, you were right. Thank you! ??