no matter ho many times I calibrate compas, imu, remote. when it's flying it always flight slightly off to the side. anyone else having this symptom with the p4p?
even when ascending it seems to slightly pan during the ascend and I cant keep if facing straight.

It's your IMU that keeps your aircraft flying straight, unless you have compass problems which I doubt from reading your post, also if your flying at low altitude VPS can have an effect on your aircraft, try testing above 10 meters to see if it's flying straight, if not I would recommend a proper IMU calibration, if it's ok at altitude then your aircraft is ok.

It looks like you have plenty of experience! but one thing that a lot of people frequently forget is from where they tak off?

Are you taking off, from concrete slab, close to metal, cell towers, high voltage power line. Do you have a phone on you, keys etc....

Try a COLD IMU and then AUTO calib gimbal. Good luck!

Same here.  I've owned 6 Phantom 4 models and they all do it.  I have to steer slightly off to fly a straight path.  I've flown all over the U.S., Puerto Rico, Costa Rica, and in rural Michigan where I live.  They all do it.

have you correctly calibrated the sticks?