rradulescu2017 Stellar has nothing to do with your case because it was working as it should, avoid using multisig until you understand it (and this apply to Stellar or any other Blockchain)
Alfy76 the 2fa is something from a third party entity to use a feature built into Stellar (the multisig feature) so basically you were using multisig even without knowing it. That's why is not recommended until you understand it because a bad move with multisig and you could loose your account forever