Though "Image Size" indicates the document is set to have a different dpi, once an image is exported via "Export As" it appears to be set to 72 dpi. Not a big deal, and I was able to save the image at the dpi I needed by using the traditional "Save As" method. All the pixels are still there of course, but the file seems to report itself as being 72 dpi. I confirmed by viewing the image in Preview on Mac (under Tools and "Show Inspector" it gives the dpi). When I exported the image from "Export As", Preview interpreted it as 72 dpi—whereas when I saved it using "Save As", Preview reported the intended dpi. Perhaps this occurs intentionally for web-based deployment, but it seemed unintuitive. Photoshop will still be getting a 10/10 rating every time that obnoxious box pops up though!