How to fit 10 speed cassette on this hub
I have experienced this exact problem except trying to fit a 4600 cassette on the same hub.

If you look at the cone, you will notice the threads expand slightly nearer the centre at the point at which they start to stick.

I will update this answer if I ever get a clear explanation for this design feature.

Update​: lbs got it on with some brute force! Presumably a one way road? Will update if it goes badly wrong.