The ParentChange does not apply a rotation of exactly 180 degrees, when caused by the change of parent (eg. the new parent is rotated by 180 degrees while the previous parent was not rotated).
In contrast, a change of rotation of 180 degrees normally works fine when it is applied as part of the ParentChange.

Attached is a small example that reproduces the issue. Changing the rotation of the blue rectangle to something slightly different from 180, say 180.00001, makes the rotation work fine.