Troubleshooting MAX30102 V2.0 (SEN0344) Heart rate sensor I2C communication

Hello, 

First time posting here so apologies if I have left anything out. I have been trying to get raw data from the MAX30102 V2.0 sensor with not much luck at all. 

So far I have found one library that works but it can't be used to obtain raw data ( https://github.com/DFRobot/DFRobot_BloodOxygen_S ). This library successfully outputs data to the serial monitor in the Arduino IDE, so it's unlikely the problem is with my connections or hardware. I have compared this library with the ones that have failed but I can't figure out why only this library will successfully connect with the sensor.  

I want to use a library that can obtain raw data and have tried several ( including https://github.com/DFRobot/DFRobot_MAX30102 ) but none of them seem to work - I get the error message “MAX30102 was not found” in the serial monitor whenever I use any of the examples. 

I am using an Arduino Uno R3 and have also tested an Atmega2560 but experience the same issues.  

My connections are as follows (MAX30102 → Arduino Uno):

3V3 → 5V (have also tested 3.3V) 

GND → GND

SCL → SCL (digital pin 19)  

SDA → SDA (digital pin 18)    

I have been struggling with this for a while now so any help would be greatly appreciated.