Mirroring does not inherit contours.

[Subpath]

When you mirror an object with a contour, it works as expected.

However, if you delete this contour and assign a new one, it only
appears on the original object.

Its the same when you assign a contour later to already mirrored object,
the contour appears only on the original.

[VectorStyler]

@Subpath I opened a bug on this, please send me the file.

[Subpath]

@VectorStyler

File is send