TMF8701 Not working on standalone

Hi! I have used the TMF8701 sensor and used the code provided by the Wiki. I used the: Sample Code 1 - Distance Detection

The code and everything works flawlessly when the computer powers up the arduino (Uno R4). However, when having an external power supply powering the arduino, the tof.isDataReady() function never returns true. I would also like to know why sometimes the initialization of the sensor fails, and i have to unplug the usb and plug it back in for it to initialize properly.

Thanks in advance!