Instance from mirrored faces obtain incorrect rotation (Bug?)

Has anyone else had issues with instanced objects acquiring the wrong rotation when instanced from faces derived from a mirror modifier. I’ve ran several tests and get the same result every time. dont want to report it till someone confirms it.

Do you mean the error appears after you add a mirror modifier to an object, then Alt-D that object?
It’ll help if you give a more detailed steps to replicate the error.

I added a mirror modifier to the plane and parented the triangle to the plane and set instancing on the plane to faces. I dont understand why the triangles being instanced from the planes mirror have been rotated 90 degrees around the z axis instead of being mirrored.