Issues printing when saved as PDF, but is fine when printed from Illustrator - White Blocks

[Gavin24249667h1nm]

When I print my file directly from Adobe Illustrator, the print comes out fine. However, when I save the file as a PDF using the "PDF/X-3:2002" settings and try to print it from Adobe Acrobat, some areas of the illustration print with white blocks over them. There are no hidden layers in the file, so I'm unsure why this is happening.

I need to send the PDF to a client, but I don’t want the random white blocks to appear. Has anyone encountered this issue or have a solution?

[Mike Witherell]

Why not a PDF/X-4?

Also, this looks largely like pixels; not vectors. Why be in Illustrator at all? Why not Photoshop?