Hi MMucka,
1.For voltage level shifter in your circuit, you need to ensure the availability of bi-directional voltage switching. If possible, nRF52832 also uses 1.8V power supply; 2.INT(from shuttle board) should be connected to nRF52832 GPIO pin 3.To provide a certain level, SDO(from shuttle board) should be be connected to GND or VDD.
You could use the logic analyzer to capture the I2C waveform and check the actual I2C communication details.
... View more