Super safety issues

First off, much appreciation for the bold lock posts. I filed my upper and fixed that. I'm having a hard time getting the super safety to do it's thing. The first few rounds go quick, but it's not repeatable. Everything after that is shooting in semiautomatic, whether I select super safe mode or semiautomatic. I ordered a full setup from DNT, didn't do the trigger modification myself. Thanks in advance for any helpful hints.