OmnibusF7V2 compass not detected

Hi all,
OmnibusF7V2 is not detecting the compass(Drotek M8N GPS+HMC5883 compass combo) running latest arducopter.

If i switch to INAV without touching any wiring ,then compass is detected and working.
Compass is wired to SCL/TX3 and SDA/RX3 pad of the omnibusF7V2.
GPS is wired to Tx6 and Rx6 pads of the board.
Smartport is wired to Tx1 pad of the board.
Sbus is wired to RC pad of the board.

Everything else (GPS,Frsky SBUS Rx and Smart Port telemetry)is working.Please help.Thanks