Hi, so I am modeling a bench and I decided for the arm, to duplicate the other arm and flip it via "Duplicate Special Option" and do a "Scale: -1.000" for the X plane. But the flipped arm won't work.

I tried to freeze transformation and erase the history by type, but nothing worked.
So once I duplicate something with a -1 scale, what should I do to make it DMM verifiable?

Image shows after I press create DMM on the duplicate piece.