Hasn't ever worked for me with the hyphens, unless they've run an update in the last month that changes that.
Try copying the key with the hyphens included and then pasting it first into your browser's address bar. If there's an extra space at the end, delete the space and then re-copy it. Then try pasting the code into Shift. That's how I've been doing it all this time. If I leave the space in, I can't paste it. If I remove the space first, though, it works every time.