Decryptbykey returns an empty string. What could be the problem?

Question

SQL

Good afternoon!
There was such a problem: the password encrypted with the encryptbykey function is stored in the database.
Applying decryptbykey to this field returns an empty string. Everything seems to be correct.
encrypted field varbinary (max), decrypted varchar (max), I open the key before the decrypt, but the string is still empty. I broke my whole head already)
SQL Server 2012