iPhone black-and-white pictures appear as color when uploaded to Mac OS X - how to fix?

My black-and-white-captured iPhone iOS 8.1.1 Camera photos uploaded (via Dropbox Camera Uploads) to my Mac OS 10.9.5 MacBook Air all appear in color in Chrome, Firefox, Safari, and Preview.app. All of said pictures look like B&W on my phone and via all of the above viewers reading any email attachment (of said B&W pics) sent from my phone. Only after Dropbox-Camera-Uploads-uploading them do they appear to be in color.

I didn't have this problem I've used previous iPhone + Dropbox_Camera_Upload configurations (I believe this included an iPhone 5S running iOS 7). I'm not sure what changed to "break" this -- it's rather frustrating.

Other users experience this problem but I haven't yet found a "fix": http://ift.tt/1xwDV0e