Osnap to Knot not working on Non-uniform Srfs after insertKnot

Knot snapping works on non-uniform crvs and crv extrusions but doesn t snap to knots on non-uniform srfs after knot insertions (insertKnot). it does snap to uniform (makeUniform) though?!
also dupEdge on these non-uniform srfs recreate the origin edge before editing (insertKnot)

bug or else?

thx…