I note that hatch patterns on mirrored xrefs mirror whether or not they are locked, this knocks out about 50% of the repetition on any project we do, coupled with the inability to xclip by fence it makes the xref tool pretty much useless for constructing construction documents. Datacad used to understand how architects needed to use the programme, now I am beginning to wonder.
The hatching mirror is caused by the Hatch Pattern Angle being locked in the XREF itself. Try re-hatching the area making sure that Angle isn't locked in the Hatch Type Menu. Now see if the mirrored XREF is fixed in the other file.
I mirror XREF'd elevations all the time without a problem with the hatching.
Hope this helps.
