Hi Anthony, that little tiny arc at the top of your shape up here:



That arc has a radius of 0.00006 units - that's not just approaching the fitting tolerance, it's quite a ways under it. That will cause all kinds of various problems - basically that arc will tend to melt away since various mechanisms will think that a line is within tolerance of it as a proper shape to represent it.

Even when you work at a better scale, that little arc at the top is still really out of proportion with the rest of the shape and you'll probably run into a lot of problems with something that has such a teeny tiny rounded piece in it that is so much smaller than the rest of the surrounding model.

Really you should generally avoid creating models that have that type of way out of proportion feature in it - it throws a monkey wrench into a lot of different kinds of things.

- Michael