Default [Q] SIM Unlock Code From T-Mobile Not Working For T999L

I requested and received a SIM Unlock Code From T-Mobile for my S3 T999L (LTE version). However it does not work. I have tried 4 times. Questions:

1. Could it be possible that the code is correct but the "PERSO SHA256" setting is set to OFF? That's the setting from the *#197328640# ServiceMode trick. I did try to unlock the phone using *#197328640# unsuccessfully. I read somewhere on the internet that it should be ON to unlock using SIM code. Are these two really related?

2. How many more times do I have to enter the SIM code before it is permanently locked?