Came across an issue that I found a solution to in case anyone else was beating their head about it.
When I export an HTML 5 version of my game and then drag the folder to my public dropbox folder (Webapp). For some reason, ONE image always seems to get uploaded outside of the images folder.
When you try and load the index.html file, you get a red loading bar, and the console says it can't find that image.
For some reason Dropbox is moving that image outside of the images folder (when it's clearly inside it before uploading).
I still need to check if the desktop sync app causes this too, but it's giving me other sync issues right now.
The solution is to simply move that image after it uploads into the images folder on the dropbox webapp. Then reload the page and you will be good to go.