Uncommanded Yaw and Sluggish/Delayed Control

Operating on a Pixhawk 2.1 and Here Gnss

On takeoff the craft immediately yaws nose right and very slowly corrects the issue and all controls have a very slow response time. This is behaving like bad PIDs are set but we manufacture these drones and have been using the same parameter file on our other drones of the same model without issue. We’ve tried completely reprogramming the craft, ESCs, and transmitter with no effect. Mission Planner posts no flags during the flight and behaves as if everything is normal. I can’t think of a hardware issue that could cause this behavior. Something we did find that is strange is that the RC input for yaw which is CH4 shows a steady and completely linear increase in pwm value as time goes on and no input was given. I can not replicate this on the bench but it occurs on all three test flights that we have done.

10092 Crash Parameters 1.24.19.param (13.4 KB)

The firmware for this flight is 3.5.7 but after updating to 3.6.5 the problem persists. This flight was the longest giving the most data.
2019-01-24 13-37-44.zip (536.6 KB)