I am having the same issue. I am setting up a mobile device attachment viewer app (using the pre set mobile device button in the app builder). Photos appear with correct orientation in attachment viewer on my laptop while configuring the app. However, upon publishing and viewing on mobile device in Chrome browser, the photos are rotated. On the mobile device, if you long press the image and select "open image in new tab" then the image displays in a new Chrome tab and orientation is correct.
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