Hi SUIYAN, that's a much different bug than the other one, they are not related.

This one is from the STEP importer having some difficulty with splitting edges that cross over the "seam" of a closed surface.

It's not just a display mesh problem like the other one.

You can still send them to me, at some point I will probably try to write a new split at seams function and it is good to have more test cases.

- Michael