Yes in .dwg export, isometric views (with views in shaded or lines removed mode) always disappear when they have multibody parts in the assembly. Think the bug may relate to unhealed surfaces in these parts. I Looking for a get around to get drawing into autodcad format.
This is occurring for me, far later than this OP. This is the only thread I could find referring to the error text, "There was an error in creating precise geometry for the following drawing views. They may appear empty." Indeed they do. All lines drawn upon the view, edges converted into lines, annotations, and blocks in the view do carry through to the DWG, but the entire assembly model is missing from the view in the DWG file.
This is occurring for me in a large assembly drawing which includes subassemblies, and both single body and multi body parts. This is only occurring for me in Orthographic views: Plan View, and three Elevation Views. Ortho views of subassemblies containing various components work fine, as do Section views. This is only occurring on one out of three drawings of unique but similar large assemblies which I am exporting to DWG files, so I cannot derive causality or differentiation between what succeeds and what fails.
I have used a very low quality workaround, PRINT2CAD, which is a PDF to DWG converter. It attempts to vectorize a rasterized PDF into DWG entities. It handles complex curves very poorly, such as sheet metal edges which blend, morph, and merge with other object edges. The DWG output is very ugly, but the straight line annotations of overhead eaves/gutters, center lines and dimensions come through cleanly. Thankfully, the purpose of this exported drawing this time is only to express the exterior of a building enclosure, with site details such as connection locations.
I have never experienced this issue before, but then I rarely export to DWG files. Reference installation 2016 SP5, Win 7 Pro, no PDM, networked file locations, and wide variety of hundreds of components included.
Edit: I believe that this error has nothing specifically restricted to multibody parts as OP thought.