HELP needed - SparkFun RGB Light Sensor ISL29125

Hello to you all,
I am new to this forum, so I hope this it the correct place to post my question.
I am trying to connect a SparkFun RGB Light Sensor ISL29125 to the Seeeduino Mega 2560 v3.0a.
I have bought this logic level converter - 5V 3.3V 2 Channel BiDirectional Logic Level Converter Module fr Arduino Rasp

I connected everything as shown to the Sparkfun hookup guide, (pins 20,21 for Mega) however when I try the RGBBasics example everything freezes.
I downloaded the I2C master library and when I run the scanner, it freezes always at the beginning and then I have to unplug and re-plug the SDA/SDL for it to receive some kind of HEX data. And not always successful.
Any ideas on how to solve the freezing issue?
Thanks in advance for your time.

How do you supply power to the module? Please provide a wiring diagram (not a photo).