I am able to add photos from my phone to my Roku device to set up as a screensaver. However if I try to add an edited version of a photo, the Roku will only upload the original version. For example I have a space picture of a planet....I tried to add a black and white version of that same picture and it won't upload the edited version.
Try creating a new photo stream and adding the edited picture to that. If that works, just make sure both photostreams are added to the screensaver. I use this method because I have a lot of pictures sharing the same name, saved to different folders. It won't rename an uploaded photo with a duplicate name, it will just fail. So I use new photo streams like new folders, rather than renaming all the files.
If that doesn't work, make sure the file size of the edited photo isn't much larger than the original. E.g., I have to resave my .png files as .jpg because the .png files are much larger and the upload fails. It doesn't seem to matter if the dimensions are larger than the display, it fits them to it. But large file sizes won't upload.