Dropbox iOS Conversion of HEIC Photos to JPG on Portrait Mode Photos not Viewable on Sierra

Not to hijack this thread, but I don't have the HEIC option in the Dropbox app (iPhone SE, iOS 11.0.2, latest Dropbox app). This is odd, as I also have a different (related?) problem where I can't enable background uploading and my videos aren't uploading for which I have a ticket open.

Just curious if you have High Efficiency or Most Compatible selected in the iOS Native Camera option? I don't think it matters, since the Dropbox app shows the option either way I set it on the iPhone 7+.

I also noticed another option that is very interesting, under Settings > Photos > Transfer to Mac or PC:

Same issue on Windows with Dropbox App! 

I created a Dropbox support ticket and directed them to this thread. Hoping they are aware of the issue and are working on it.

You can change the format back to JPG but if you've already used the HEIC format, the only thing you can do is convert your images. There are few converters already and I found this Free HEIC Converter to JPG. This works perfectly as I was able to change the format of my images without losing the quality of my pics. It's free and does not require installing additional software as its an online tool. 

So I have a file with a .jpg extension that cannot be opened Sierra but can on High Sierra.

Let's assume it is really a .heic file but has an incorrect .jpg extension.

Now I change it to .heic as you suggest.

What exactly would the next steps be? And how would those steps prove your theory?

There are no next steps. It was simply a suggestion for when you come across a JPG or HEIC file that wasn't recognized (by the file's extension) and couldn't be opened. Changing the extension may allow you to open the file because the extension would then match the file type and the operating system would then know how to handle the file.

Going back to look at it, the Dropbox iOS app was uploading HEIC files and renaming them to JPG, but not actually converting them. Changing the file's entension from JPG to HEIC allowed the file to be opened normally. No data was being lost. This issue was corrected.

On High Sierra, there was no problem opening the heic file, even with the .jpg extension. So changing the extension to .heic changed nothing (it still opened on High Sierra, and still could not be opened on Sierra).

But the real problem was that Dropbox was not converting heic files to jpg when the setting was on.

Now the problem has changed a little. Under most native setting conditions, Dropbox never converts the heic to jpg, so although it correctly keeps the .heic extension, the resulting file is not easily shareable.

I have since gone back to change the native phone settings to "most compatible (JPG/MP4)" until Dropbox can get it worked out. Also, it turns out that heic photos actually are of lower quality than jpg in many cases, and since I have 256GB, I'm not really concerned about space that much. The new video file would be important to me, however.