There was a bug (Windows-only, fixed in 2020 SP2) where VPs might show black when default image compression preference was set to JPEG (instead of the default which is PNG compression).  Don't know if that is the issue here.  If it is file specific that helps to know.  If it is machine-specific that is helpful to know too.  Can you strip out any proprietary stuff you can't share and post the VWX file here so we can try it?