Also, if the airplane always rolls left on inside loops, and always rolls right on outside turns............

It just might be P-effect.

Depends on the power of the engine, size and pitch of the prop, and a few other factors for how significant P-effect can effect what it effects. But it happens.

The prop sees a favorable change in AOA on one side of the nose while the other side sees a less favorable change. Has to do with the upgoing blade versus the downgoing blade. It's real and causes the fan to pull in a yawing direction. And when you yaw an airplane, the faster wing gets a favorable change in AOA while the other gets a degraded AOA. Sound familiar? We can usually see roll pretty easy. Seeing yaw ain't so easy.

It just might be caused by this.
This effect happens more than we usually identify. How often do you see a model that's taking off turn left. Nose is pitching up on what amounts to an inside loop (sometimes more loop than takeoff) and the p-effect gives some yaw. This has a probability of effecting what you're seeing about on a par with how often you see your model want to turn left on takeoff. That said, if your model has tricycle gear, discount the amount. They don't pitch up as much on takeoffs. Anyway.... it's worth considering.

It's also a fact that if something else is the main contributor to what you're seeing, p-effect will keep helping yaw left on insides and yaw right on outsides. So don't look for a cure that tests out with complete removal of all rolling.