I have investigated further and finally figured out that the problem is with the photograph’s dimensions. All of the photos that were tagged with the program name “Microsoft Windows Photo Viewer” were rotated from landscape to portrait on import. Their dimensions are 3000×4000 rather than 4000×3000 like the photos that will upload. After trying to save the photos without their metadata and various other edits, it turns out that for some reason I get the “imagick”” error only on the photos that have a dimension of 3000×4000. Changing it to 2250×3000 allows me to upload them, but this is still a pain and needs to be fixed on WP’s end. Again, this was never a problem until after yesterday’s upgrade to 4.5 (and sadly my auto-backup was turned off somehow so now I am stuck with this).
