Is there an error message or some type of prompt that pops up when it fails to upload your images? Is the same thing happening for videos for you too?
@Lester - Do you experience this only on your iPhone/iPad? Not on your pc? I will do a test on the iPad to see if I can replicate the issue.
@Dank - You have the same issue on firefox (but works when you edit your post to re-upload the image) - have you tried on different browsers?
Let us know and we'll go from there.