Incorrect throttle behavior

I’m setting up a Skywalker X-1 using a pixfalcon. I started with the X5 as the basis and disabled the air speed sensor. The issue is that, once armed, the throttle doesn’t engage until half way. I checked using a servo tester and PX4’s output is 997 (or something "low) until I raise the throttle past halfway. Then is goes from 1000 up to 2000 at full throttle. I checked the mixer file and it looks correct so I took a look at the logs.
If you look at the throttle goes from -1 to 1, the below that you can see the Actuator 0 controls has the throttle from 0 to 1 (which is correct) However all it’s done is throw away the -ve portion of the RC input, so I can see why the throttle is behaving the way it is. Isn’t the Actuator value what is sent to the mixer? If so the mixer will never work correctly. I’ve only used PX4 for multirotors previously so maybe I’m not understanding the channel mappings correctly?
This behavior seems consistent on 1.6.5 loaded via QGround Control, “Beta” via the same, and building and uploading from the master branch.

Fixed! Recalibration with QGroundcontrol fixed it @dagar pointed out on slack that the throttle was calibrated at exactly 1000->2000
RC1_MAX, 2000.0
RC1_MIN, 1000.0
RC1_REV, 1.0
RC1_TRIM, 1500.0
RC2_DZ, 10.0
RC2_MAX, 2006.0
RC2_MIN, 982.0
RC2_REV, 1.0
RC2_TRIM, 1495.0
RC3_DZ, 10.0
RC3_MAX, 2006.0
RC3_MIN, 982.0
RC3_REV, 1.0
RC3_TRIM, 1496.0
RC4_DZ, 10.0
RC4_MAX, 2006.0
RC4_MIN, 982.0
RC4_REV, 1.0
RC4_TRIM, 1494.0
RC5_DZ, 10.0
RC5_MAX, 2006.0
RC5_MIN, 982.0
RC5_REV, 1.0
RC5_TRIM, 1494.0
RC6_DZ, 10.0
RC6_MAX, 2006.0
RC6_MIN, 982.0
RC6_REV, 1.0
RC6_TRIM, 1494.0
RC7_DZ, 10.0
RC7_MAX, 2006.0
RC7_MIN, 982.0
RC7_REV, 1.0
RC7_TRIM, 1494.0
RC8_DZ, 10.0
RC8_MAX, 2006.0
RC8_MIN, 982.0
RC8_REV, 1.0
RC8_TRIM, 1494.0
RC9_DZ, 0.0
RC9_MAX, 2000.0
RC9_MIN, 1000.0
RC9_REV, 1.0
RC9_TRIM, 1500.0