Fan xpert 4 /Ai Suite Fan tuning detects wrong fan speed

Got about 6 corsair fans, 2 controlled by water cooler
And 4 via pwm on asus rog crosshair hero wifi (cpu_opt, cha1-3)
When fantuning runs, it detects one of these 4(cpu_opt) fans as minimum 5200 rpm and maximum 5700 rpm.
All the fans are corsair ll120 rgb fans and rest all are detected fine.