Unexpected PWM values leading to take-off failure

Hello, I am trying to setup my pixhawk with apm 3.2 version to control an Octocopter. I am using a game pad through the mission planner to act as the transmitter
to fly the Octocopter (http://copter.ardupilot.com/wiki/common-optional-hardware/flying-with-a-joystickgamepad-instead-of-rc-controller/). I also bypass the pre arm
checking in order to bypass the RC calibration process as well as other processes. So far I am able to arm/disarm the pixhawk, control throttle, send target roll,pitch,
and yaw values through my gamepad.

However after arming the pixhawk and having motors running when using Stablize mode, I am unable to get the Octocopter to lift, even if I hold down my throttle button to increase speed to the max.
After looking at the status data on mission planner, I saw that the RC outputs 1…8 were noting sending the pwm values i expected. For example when leaving the throttle stick in the center
I expected all the RC outputs to be sending a value of 1500 instead the ACTUAL RC outputs where close to 1500 but ranged from 1200 to as high as 1600, and if I push the throttle stick
to go max throttle which I thought is set to 1900, the ACTUAL RC outputs do not reach those numbers and can range anywhere from 1300 to 1800. I did find that pulling the throttle stick
to min throttle made all the RC outputs go to 1170.

I did look through forums and came across this question http://copter.ardupilot.com/wiki/common-appendix/troubleshooting/#my_copter_motors_spin_but_the_copter_wont_take_off_or_motors_may_not_spin_at_all and found that parameter THR_MAX being too low might be the issue, but in my case THR_MAX was set to 1000 which is the maximum value it can be. I also made sure that propellers are all rotating correctly,
I am using a OCTO X frame.

In terms of hardware, this octocopter frame & components have been made to be overqualified for flight especially without any camera or other attachments. Motors are KDE 4012’s w/ 18x5.5 APC props (training wheels for now, replacing w/ CF props after several successful flights), and hobbywing xrotor 40A esc’s. Total weight is still 30% of max thrust.

I’ve yet to encounter a situation like this with my previous setups, I have ran out of ideas and would really appreciate any solutions or idea.