PDFs printed from Mac turns viewports black - still. Files created on PC

I have not found a solution to the printing issue that Macs are having printing PDFs. My SU and LO files (SU v.2020.0.373) are created on a PC. I export them to a PDF, as I have for many years. When my engineer prints them from his Mac the viewports are blacked out. I have read that this has been fixed, but I am still having an issue. Does anyone know how to correct this? I know I can send a .DWG file and I did, but a PDF is easier.