Tarot IM 1100mm HELP!

Hey there Arduino world.
I need some help diagnosing an issue with my Tarot 1100mm Octocopter.

I have 2 motors (#6 & #7) running full when plugged into battery (without calibration of ESC via Transmitter ... video 2) and then when ESC's are calibrated, those motors seem like they get little or no signal...
They get a good signal and work fine with a servo tester when testing them individually, but when plugged into the FC they act up and dont respond to throttle commands

Here is my setup

Tarot IM 1100mm Frame
8x Gartt 300kv ML5010L motors
8x 40a Readytosky ESC's
Hobbyking high voltage octo PDB
APM 2.8 MEGA with newest stable version Octo firmware
2x 6S 3300mah parallel
1555 Tarot CF rotors (balanced)

Here are the videos

The one motor not working at all I will be swapping the esc to see if it's just bad or if it's the brand new motor...

Please help

Well if you want an Arduino related answer, it would be connect Arduino to the FC channels 6 and 7 using pulseIn to measure the signals its giving out to see if they have a problem.

But you could just swap a good and bad channel to figure out whether the issue is FC or ESC/motor...