I would check the back side of the prop first, I've had several APC props that needed deburring on the back side. This never does seem flat either, I have no idea as to why they make it this way.....?
Traditional props always have a flat back side as far as I know.

So flatten the back and add a thinner washer, that might be enough. And don't forget to balance it, the holes are often off center and it looks like your's is as well...