I figured out what was causing it, but I'm still fuzzy on the exact reason why. In Photoshop, you can choose between various rendering intents. When I use "Relative Colormetric" it prints white as no ink. If I choose "Absolute Colormetric" it print white as a very light grey.

From the descriptions of these in Photoshop and other places, I don't really understand why Absolute Colormetric would have this problem. Here is Photoshop's description of Absolute Colormetric:
My best guess is that for whatever reason, Photoshop decides that white is out-of-gamut and shift it to the very lightest gray that the printer can produce. It seems to me that white should always be in-gamut, but I'm new to all this.

The driver is set to Off (No Color Adjustment). I sent an email with the profile. Thanks for looking at this.

I made a profile using Profile Prism and the colors look great. Much better than the stock profile. Everyone is impressed with how nice the prints look.

The only issue I have is when I print using the profile, white gets printed as a very light grey. Most of what I print is papercraft items, and the tend to be PDFs. These pdfs have large white areas. Using the stock profile, white is no ink, but when using the Prism profile white areas are printed as a very light grey. I don't know how much ink is being wasted by printing the white portions, as it's a very, very light shade of grey, but I'd rather have white be white.

I can open the files in Photoshop and delete the white to make it transparent. But some of the files I print are 40 pages long, and it can be rather tedious.

I have this issue printing from Acrobat Pro and Photoshop. Both Absolute and Relative Colormetric do this. I can verify that the color in photoshop is 255,255,255.

Is there something wrong with my profile? Is there some adjustment I can make to force it to print 255,255,255 with no ink?

Scanner: Epson Artisan 730
Printer: Epson Artisan 730
Paper: Staples white card stock
Purpose: Making paper terrain and other papercraft.