I'm a premium member. I just updated and activated the new Update plugin. Upon following the link to get my API key from the WPMU site, it doesn't recognize my login password.
I can log in directly to the site with my password, but when I select almost any link, the site logs me out. For example, I log in to the main page, click on the link to my profile, and I get logged out. Another example, tried to go to live support and got logged out. I can log back in and the current page remembers me, until I try to navigate somewhere else.
Looks like something is going on with your site, maybe related to permissions or membership status. I believe we're all paid up so membership status should not be an issue.
Appreciate any advice you can offer...