Just a thought, did you try renaming the image altogether. In otherwords, don't call in logo.png again, or whatever. Try something like logo2.png or something. I know sometimes in web design there are issues with cache when its the same filename.
Did you try it on one Roku device? I noticed that some devices dealing with updates differently.
Try with Roku 3, Roku TV, Roku premier and Stick.
Any solution? I have exact same issue. I am showing as having published version 20, but the Roku store shows version 15.
What browser are you all using?