Recently on xDesign I cannot succesfully mirror parts anymore. Parts in assembly are mirrored, but all features are lost with an icon with red lightning bolt on it and cannot edit them anymore. I've tryed to create new parts in the assembly, to import parts already prepared, to "Save as..." parts in the assembly, import them andt hen mirror....an so on. The result is in the image attached.

I have no idea what else to try nor what I'm doing wrong. Before summer I worked on several files mirroring parts with no problem at all. 

Please help !