That is not expected, the phone should have such a big influence on the I2C or sensors.
A flat ribbon cable is bad for I2C. When the SDA or SCL changes from high to low, it might cause a peak in the other signal. The SDA and SCL can be best short wires, not close to each other (not long wires with tyraps to keep them together).
The Arduino Uno is a 5V Arduino board, and the sensors are 3.3V. The SDA and SCL are now only 3.3V when being high instead of 5V. It should work, even if that is a little outside the specifications for the ATmega328P chip on the Arduino Uno board.
The signal levels do not match very well. You could fix that with a level shifter.
I use these : i2c level for sale | eBay
If the problem can not be solved, the first thing to do is using a level shifter.