so, i'm using walls for units in a multifamily buliding. using 4" standard wall style, have them cleaning up properly. most units i can xref into the building layout plan and mirror and rotate and the walls still clean up. however, this one darned 2br unit - it xrefs in and the walls clean up fine UNTIL i mirror it. then all the walls disappear and show yellow delta exclamations.
my workaround is to take the original xref, and saveas as UNIT B1 FLIP and then just xref the original and the flipped version as needed. it's working, but dang i wonder what in the world could be causing this.