...I get redirected to the main page. There might be another thread on this issue, but I haven't found it. Thanks.

So whose account are you on now? :o

I meant that I can't see my library, account settings, wishlist, etc.

I think this is the link to do a 'refresh' on your account login stuff:

https://www.gog.com/user/refresh

Did you use the 'Logout All' button from a different computer?

It sometimes halfway logs you out on other computers. You can use the forums but can't access your account for the most part. Clear all your cookies and you should be able to login again with no issues.

Thanks, all. Clearing cookies worked.