Galaxy 2.0 won't let me log in 99% of the time. What could be happening? Why has it logged before and now it won't let me log again? Any thoughts?

Note: I get that only that message and it keeps reloading it after I click the button.

Weird. You obviously can log in fine into your GOG website account. I'd first try to "reset" log ins in other stuff, luckily on GOG Galaxy too. So go to -> your account -> privacy and settings -> under 'Authorized sessions', click 'LOGOUT ALL'. (you might have the hassle to input your login on other machines and stuff.

Then, run GOG Galaxy again. Hopefully, it will ask again your GOG account information, see if it helps?

If not, I'm out of ideas.

(If you use GOG in Brazilian Portuguese, let me know.)

EDIT: I imagine you already tried to uninstall GOG Galaxy and installing it again.

That was my thought too, as (at least running it on windows) Galaxy is not using the proxy settings