ASRock B450m Pro4 + NZXT H510 Chassis Fan problem

[LS18]

Hello All!

I do apologies if this has been covered, I have searched for quite a while! I just completed my build yesterday using all brand new components.
 

My issue is - the two 3-pin Aer 120mm fans in my NZXT H510 are connected to CHA_FAN1/WP (rear fan) & CHA_FAN2/WP (top fan).

Both spin! However only 'Chassis Fan2 Speed' on CHA_FAN2/WP RPM is being registered in the BIOS/A-Tuning. 'Chassis Fan1 Speed' is displaying 0RPM same with 'Chassis Fan3 Speed' (which is not being used).

I did some experimenting - I swapped them and the top fan registered RPM on CHA_FAN1/WP and rear fan on CHA_FAN2/WP still did not. Originally I thought the problem was CHA_FAN1/WP header, however, after this experiment It seems to be the rear case fan itself - any fix suggestions?
 

Thanks for your time, it is very much appreciated!
 

Cheers