To add to this, When I xref in a civil 3D drawing using Map, I can snap to structures using “insertion” snap. I can also snap to contour labels with insertion but not pressure network labels and not alignment labels. I can insertion snap to pressure network pipes. I can snap to end points and mid points on alignments and contour vertices, but not pipes from pipe networks. Not end point, not insertion, insertion works only on structures and there are some additional snaps that work on the structures in the actual drawing but only insertion through the xref.
When I use Civil 3D to open both the C3D drawing and the parent drawing with the C3D drawing xrefed in, snaps behave consistently regardless of which drawing I'm in.
I haven't tried every object possible but so far, it seems like the issue is in the object enabler for C3D not interpreting pipe network parts correctly or at least not enabling AutoCAD snaps to the same extent as a non-xrefed C3D drawing.
