Bad tracking is caused by either the engines drive washer or the flat of the rear of the prop hub. Not usually the drive washer. I have had to sand the back of some prop hubs to get the tracking right. Biggest trick is keeping the surface flat as you remove the side which brings the tracking back on line.

Another thing. When I check tracking I always make sure the plane is firmly secured so it does not move at all when turning the prop. Also, I remove the glow plug to make turning the prop easier.

One problem I found with the nylon props is if you have a prop strike it will sometimes bend a blade, and it will stay that way.

Just for the sake of experimentation, when checking one of your props that shows being off, bend one of the blades forward or backward and see if that doesn't correct the tracking. If it does. check it again the next day to see if it stays that way.

In my opinion tracking can cause vibration, but I don't believe it is as critical as balance.

Just my two cents