Maighstir: It seems the front page and catalogue has problems understanding whether or not a user is logged in.
I have this from the first moment I visited GOG yesterday (after the sale had already started) - the home page just won't let me log in, unless I use IE.
Here's a new oddity - opening the "Browse Games" page, the games I own are marked as such though the page insists that I'm not logged in. But when I open any of their gamecard, the game's available for purchase. The system even lets me add it to my card, but then asks me to log in which always fails and I'm asked to log in over and over again.
I think that something got broken when setting up the sale and that it's not my browser. But then, I can't explain why it lets me log in with IE while I'm already logged in with Pale Moon.
EDIT: I've solved the mystery of the log-in problem on the home page. It's caused by the home page not working properly with the HTTPS Everywhere add-on. Something definitely changed on the home page for the sale and if you have that add-on enabled, log-in breaks. Disabling it for GOG and clicking on the home page link from within the forum resulted to the home page recognising I'm logged in.
To anyone else having the issue, check if you're using the HTTPS Everywhere add-on and disable it for GOG.