I have a customer I'm working with that is having an issue viewing my PDFs. We sent this PDF to a bunch of people and they all view it with no problems. I asked them what they are using to view it and they are using the CC with Adobe Acrobat DC. They say it is all up to date. Any help with this would be great. Thanks!
Tell them to go to Edit - Preferences - Page Display and tick the "Show large images" box.
Also, ask for a full window screenshot. Sometimes people think they're using Acrobat when they are actually not.