HunchBluntley: I doubt it's anything to do with that, since I rarely sign out (and certainly haven't recently), and I'm still affected.
Ice_Mage: To double-check, you're missing all the numbers in the user menu at the top of the page?
I haven't seen anybody complain about the numbers missing from the dropdown menu [EDIT: I now see the couple people complaining about this :P ] -- it's the profile where games are missing. The OP of this topic is complaining about the numbers in the dropdown not being correct -- specifically, being out of date. And that's the case for me. Only one of the two freebies from the the last big sale is counted (that is, the sum of the "My collection" and "Hidden" categories in my library is one more than the number shown after "Games" in my account dropdown).
EDIT: So, to reiterate, my games no longer appear in my profile (which I don't care about at all, except that it's just one more bug on the pile), and the numbers in my "Your account" menu bar dropdown are present, but outdated (which is only
slightly more annoying than the profile bug). I have not logged out or cleared my GOG cookies since before this bug arose.