I have exactly the same trouble than user 14260550 : i can't authenticate on certain sites (found 2 sites) asking for email and password (web site error : "Forbidden. You don't have permission to access /page_name/ on this server". This bug appears with all my browsers (Firefox, Chrome, Edge) last versions.
I have mentioned this "bug" on community chanel, without any workaround (except than deactivating the extension and clearing cookies when accessing these sites). Everything worked perfectly before with version 7.21 (from memory).
Apart from this big trouble, web clipper works fine for me !

This works really well (most of the time) and I use it to save interesting links and some articles for further review and further research, or just to be able to search and find a link latter.
HOWEVER THERE IS ONE MAYOR FLAW - IT DOES NOT WORK IN PRIVATE MODE.
This is madness?
I have been forced to use Pocket for these sites.
Please fix it!

Why when you are adding site to categories: scrolling is so painfully slow? It is like slowest scroll speed possible LUL... At least you can bring it up with the hotkey `

非常给力，终于可以在火狐浏览器使用印象笔记了，唯一的遗憾是地址栏里中的扩展图标是黑色的，能不能绿色呀，黑色会被很多主题底色遮住，看不到印象笔记的图标，不方便使用

This add-on has been finally updated after two and a half years! It was dysfunctional in some areas, i.e. the Web Clipper couldn't save YouTube-links anymore (the Chrome version, of course, would always get updated). As a customer paying for their premium service, this negligence on Firefox was pretty infuriating. I'm thankful that this add-on works as intended again and hope that Evernote does not drop the ball again in the future.