If you click on the yellow star in the URL bar and the pop-up window doesn't open to let you pick a folder to save the bookmark in, see if you are running HTTPS

If you click on the yellow star in the URL bar and the pop-up window doesn't open to let you pick a folder to save the bookmark in, see if you are running HTTPS-Everywhere. Turning off that extension got bookmarks working for me again. Alternatively, you can copy and paste the URL into a new tab and bookmark it there fine, even with the extension on. If you're trying to reproduce this bug/?feature? consistently I can give you steps that make it occur 100% of the time.