If you are unable to link a social media account to your Earn Alliance account, you might've accidentally created an Earn Alliance account with your Twitter or Discord in the past. To resolve this, simply:
Log in using the method you're trying to fix, either Twitter or Discord.
Unlink the social account from your profile. This can be done by hovering over your socials and clicking the X.
Log out from the account you just unlinked your socials from.
Log in with the Metamask wallet connected to your desired Earn Alliance profile to guarantee you're going to the account with the correct wallet.
Link your social media account to this account.