I'm having some problems with updating an Impression file with altered CAD layers and not sure why. I have imported a viewport with import units set to millimeters at size A3. As a test file I only have 3 layers in the file. If I alter one of the polylines in AutoCAD save and then use 'Update CAD Geometry' to quickly update the impression file, the layer I have changed vanishes. I think it seems to be updating it at much smaller units (mm rather than metres) although I don't why. I've tried importing at metres too but I have the same problem.
Is there something i'm missing when updating the file?