motor pwm output is not working when using Timer1Ch1N

motor_pwm_init not working ,timer_alloc_tag get timer channel info from gpio_pin.in when the timer's channel is 'N' , eg GPIO_PIN(B, 1) GPIO_AF(PIN_B1, 1, TIMER_TAG(TIMER1, TIMER_CH3N)) on neutronrcf435mini 's brushed mod target