Ed v2.1.2
iPhone 6+

This may be an iOS issue in that perhaps I missed a step, but I believe @Eke tried to get this to work as well.

1. touch "edit" in a post with an image
2. touch "image"
3. touch "upload new image"
4. See the preview image not update. This feels like nothing is happening to the user.
5. touch "close" and see the upload progress or correctly replace image

Video:
https://www.dropbox.com/s/i1yv6rc8485qwpu/Ed-preview-swap.mov?dl=0