Try to crop a 6003 x 4002 image to 6000 x 4000 in one go.
You click and drag, then release your LMB. Now your image is 5999 x 3998.
You zoom in your image to get better precision and try again, and this time you get 6001 x 3999.
....
Please implement Photoshop's Canvas Size (⌥⌘C) feature into ACR.
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