Not quite sure what's up, but the Account Upgrades link is missing from navlink and account page in all styles (testing with the default style). I imagine it has something to do with $xenCache conditional, but I'm not sure how that works.
Oddly enough, this just happened on my forum, too.
I'm not sure when, exactly, the link disappeared; I only found out about it because my users noticed it was missing. Sure enough, Mike's suggestion of editing and saving a subscription resolved the issue.