H7 and HAT : I2C2 not routed to I2C4 on STM32H7

Official Hardware Portenta Family Portenta H7
2

After digging into the STM32H745 datasheets, I came aware of the following regarding I2C4 :

H7 - I2C4_pins2
H7 - I2C4_pins2796×612 99 KB

It seems the I2C4 peripheral is sharable on multiple IO-pins, including the DCMI pins D2/D3 - so layout looks to be correct.
Checking the IO pins PH11 and PH12 in the H7 Arduino library, these are used for I2C pins : SDA2 and SCL2 :

Pins_arduino
Pins_arduino913×612 140 KB

This means the pre-defined Wire2 should be working : (Wire-Library Wire.cpp)

#if WIRE_HOWMANY > 0
arduino::MbedI2C Wire(I2C_SDA, I2C_SCL);
#endif
#if WIRE_HOWMANY > 1
arduino::MbedI2C Wire1(I2C_SDA1, I2C_SCL1);
#endif
#if WIRE_HOWMANY > 2
arduino::MbedI2C Wire2(I2C_SDA2, I2C_SCL2);
#endif

The fact is unfortunately : its not working.

Tested on a Portenta C33 board with HAT : works fine. (also Wire2)
Testing on a H7 board with HAT: doesn't find the I2C peripheral.

Any suggestions ?