Extrusions gone crazy!

I have been working on the interior of a large sailing yacht. I extruded a couple of solids that are very shallow in nature to be used as mirrors in appropriate locations. So the other day I open the file to work on it and the particular extrusions now don’t appear but a wispy outline of what they once were does show. It shows through everything else as well on screen but not when rendered. I am using an AMD Vega 56 graphics card with 8 gbytes of hbm memory and an Intel I7 3930K with 32 gbytes of memory. This unique display anomaly is a new thing indeed and may relate to the latest AMD driver update though I’m not sure. Any recommendationsdisapeared extrusions as seen rendered beside building the dream machine I’ve currently salivate over?