Can't export halftones to pdf without losing color.

I just created a file and used pixelate > Color Halftones to make a halftone gradient. First time I've tried that. It essentially created a series of black dots on a white field that get progressively smaller as they go. Essentially making it look like I have a white circle in the middle of a black page taht slowly gets lighter as your eye goes toward the center due to the diminishing size of the dots. Neat effect.

However, when I edited the gradient to make the effect irregular, Illustrator began to add a blue color to the dots. I was working in a black, grey, white pallate so that didn't work. To fix this I looked up an answer that said to select that layer and make it grayscale, which I did. It elminated the blue and I thought I was set.

BUT, while it looks good on screen, when I export it, the dots that are normally black are a washed out gray color instead. There is also a very slight whiteish gray line around where the original circle would be, but only if I'm zoomed out to a smaller magnification, when I zoom in that goes away. While I want to fix both things, the biggest thing is I would like to be able to export this file to pdf without the color loss. It does the same thing when I export to jpeg. Any ideas on how to set the export up so that it will retain the black and white of the effect?