Can you enter about:profiles in the address bar, create a new profile and test it there? Thanks.

No it doesn't solve it, same issue

Interesting.

1. Try to right-click Add to Firefox button and select Save Link As… from the context menu to download XPI file.
2. Click the menu button , click Add-ons and themes and select Extensions.
3. To add the downloaded add-on to the list of available add-ons, drag and drop the file into the Add-ons window.

Thanks, that worked, is there a way to get the normal way back or i need to use this workaround until next update and hope they fix it?

I don't know. This is the first report here on SuMo. I can't reproduce it, so it doesn't affect a large population. Perhaps it's only you, so I can't say that anything would be done about it.

Highly doubt it is only me, but yeah, most likely very few, i will try to clear all extensions and clear cache and see if this helps, maybe one bugs out the button or something on the site, or next update will fix a broken file. Anyway, thanks for the help.