F450 drifting with AC-3.5-rc in AltHold mode

I am using DJI f450 + Pixhawk MINI + AC-3.5-rc. I took off in AltHold mode. The drone seems to keep leveled. However, it is constantly drifting in random directions. I am wondering is this normal? I see online people can fly f450 very stable and fixed in position. What might be the root causes? Calibration error, GPS signal not good, PID tuning not good, or weight unbalanced? Also, what methods can I use to debug this issue.

Where you in Position Hold mode or Altitude Hold Mode. One only holds altitude not position.

I have also had issues with Position Hold not holding and drifting Left. If I Yaw the copter 90 degrees it starts to drift to the Right. So if it’s center stick issues that it should always drift in the same direction.

Mike

Thank you, do you know how to get flight data records using Qgroundcontrol or mission planner? I think looking at the GPS and IMU data would help diagnostic this problem.