Hello.
Yes, we know about this problem and research it. In some devices Samsung lock not reset with this procedure. As soon as we research the problem we will contact You.
To reset Samsung Account You can try to do the following:
1. Create a new Samsung account (via PC or via another phone). You should have a working Samsung Account.
2. Perform the Reset FRP/ Reactivation operation.
3. When the phone will ask you to enter Samsung account data - enter Samsung account data, which you have created earlier.
4. Restart the phone and connect it to Wi-Fi.
5. Go to
https://findmymobile.samsung.com/ and log in with the username and password (which you have created earlier).
There you have to select the phone that was just added to account, select "Unlock my device" and "Unlock Reactivation lock".
6. Restart the phone and check whether account is reseted.