If the sketch plane and the geometry are not on the same plane, arc center is not selectable to apply coincident or midpoint constraint even with selection scope "Within Work Part Only".
Solution
Because the new sketcher does not support directly constraining to non-linear edges that are not parallel to the sketch plane. The edge has to be parallel to the sketch plane to be selectable in the Make Relation functions. The WA is to use Include Curve function to include the center of the circular edge manually and then constrain to the resulting included point.
Notes
Notes