Question Why does "Crop Pages" in Adobe Acrobat DC fail to crop my PDF?

[scherz0]

Please see the GIF below. You can download the PDF here.

Here's my goal. In the PDF, all pages are bordered by white blank space, but the white blank space start at different lengths from the border. Scilicet, the cutoff and dimensions of the text and images differ for each page.

Unquestionably it's too inefficient to measure the cutoff of white blank space on each page. So I'm cropping to eliminate the maximum white space, without cropping any of the substantive content.

 

[Ralston18]

Are you selecting "All [pages]?

Then setting and saving the margins?

Do remember to test on a copy of the document in question - not the original document.