Using pins D9 & D10 on the MDBT42Q

I checked the ID107HR plus pinout again - it is here and it uses both pins for HR sensor but only one of them is in fact I2c

...
8	SI1143_INT
9	SI1143_LED
10	SI1143_SDA
..
18	SI1143_SCL

so if it really doesn't work for you maybe it is not coincidence they have scl on 18 and not 9. Th nordic note says

The pins dedicated to the NFC antenna function will have some limitation when the pins are configured for normal GPIO operation. The pin capacitance will be higher on those (refer to CPAD_NFC in the GPIO Electrical Specification below), and some increased leakage current between the two pins is to be expected if they are used in GPIO mode, and are driven to different logical values. To save power the two pins should always be set to the same logical value whenever entering one of the device power saving modes. Please refer to INFC_LEAK in GPIO Electrical Specification for details.