All servo outputs at 1500 PWM at zero throttle

All of my motors are receiving a 1500 PWM (the value of my trim) signal even when my transmitter has the throttle set to zero. When I arm the copter all of the motors immediately start spinning.

SERVON_MOT_MIN=991
SERVON_MOT_TRIM=1500
SERVON_MOT_MAX=2016

When I reduce the trim to 991 it works fine which makes me think the problem is copter is thinking that the trim value is the min?

Does anyone have any suggestions?

I’m using BLHeli_32 ESCs

Thanks