Many of what appear to be arcs in a drafting view are not true arcs but projected splines. For the sake of getting a radial dimension, most of the time Cimatron can assume the spline to be an arc. But when the spline segment is very small this assumption is blocked by a default tolerance value. Instead of a radial dimension you will see a segment length dimension.
This can be prevented by using a smaller value in the Drafting Preference "Spline approximation tolerance for radial dimension". As long as this number is smaller than the assumed arc radius, the system will be able to calculate the approximate radial dimension.