When you began the grind, I suppose you started with a very light cut to ascertain the position of the wheel? Now it is very simple to take lots off the front of the tooth face because it is 'easy going', but not so easy to get the wheel down in the gullet and remove a considerable amount of material to keep the rake face of the gullet exactly the same shape as it was before. I suspect you have decreased the positive rake of the tooth face, which makes the tool less free cutting.
Solution? I don't know if the large wheel diameter is the cause of the problem, but try another tool, and be very observant of how much you are taking off the tooth face. You might have to just change the start angle of the tool in the indexer.
I suppose if you have an optical comparator, you could slice off a section through an original tool, and a resharpened one, to compare the exact contour you have achieved.