So I am beside myself with this. I have reformatted my system now 4 times to solve it. The issue is that when the flight model is set to anything other than Easy, the plane always yaws off to the left - badly. My controller assignments are perfect. I have also tested against two separate installations of FSX, one Steam and the other non Steam. The problem is there and completely repeatable. It even happens when there are no controllers hooked up to the computer and only the keyboard is used.
I recently was forced to do a system do-over due to some other issues that could not be prevented. Before that was done, everything was perfect. The system is the baseline as far as Windows goes with only the rock bottom necessary software installed on it. Does anyone have any knowledge of such a situation? P3D v2.5 doesn't have the issue, nor does DCS. I'm really wanting to pull out my hair over it. Any help is appreciated.