I understood that you can not make new uploads at 3.3V Arduino with your converter. the fact that the pre-loaded program work does not mean much because you only this feeding the Arduino. if the question is about having bought Arduino defective, and recording using another Arduino as ISP, this will show for you. if record, the problem is the pair converter / Arduino 3.3v. use another Arduino as a recorder. look in the Arduino sketch the ISP and you will understand the interconnection pins.
if I get it wrong, forgive me, it is the difficulty with the language.

You have an Arduino Uno? Try with this. Arduino is ISP.