I have characters in two regions, NAE and EUC, the second being the main one. Since today’s maintenance i can’t seem to go back to my main account in EUC as it keeps saying it’s locked. I can switch to South America and NA West, but i can’t to EUC. Tried deleting config folder, reinstalling the game. Neither worked.
Hello @Dremesis
Greetings and welcome to forums! 
I am sorry to know that you are unable to select region EU-C. Thanks for sharing the troubleshooting that you already performed. Please, also try, the steps that I have mentioned below-
Kindly check for game update manually from steam client.
- Steam library>Right click the game > Properties> Update tab.
- The following link has more detailed information about update settings-
Steam Support :: Managing Steam Downloads & Updates
- Restart the PC and check.
- If the issue persists, run a steam files verification check Steam Support :: Verify Integrity of Game Files and restart PC.
I hope this helps!
Let me know if this works for you 