Undercooked areas in chicken breast even though thermometer reads 165 degrees in thickest part
If the raw spot was in a thin area, I'd suggest that it was caused by the pan frying method.

A thin spot could leave a gap between the surface of the pan and the meat itself, and so not absorb much heat.

To reduce these indentations, you can mechanically reshape the meat before cooking (e.g. squash down the higher parts).

In addition, or instead, as soon as you start cooking, it's a good idea to use the spatula to briefly press the meat onto the pan's surface.
This will flatten the bottom face of the meat and give it uniform contact with the heat.

By the time you turn it over, the meat will have become firm, so you won't be able to fully flatten the second face against the pan, but that's okay as the thin parts will already be mostly cooked and the parts that still need heat will be in contact with the cooking surface.