I did the following: drop an image in my Ubuntu One folder on linux, wait for it to sync, refresh my Ubuntu One Files app on my Android phone, see the image file in the listing. Tap the image file name.
Expected: the image downloads, and I can use it as my phone's wallpaper.
Actual: it displays a preview of the image but doesn't download it and the file name remains greyed indicating "not present on device". There is no feature available from the preview except "share link". Long-press offers "share link", "rename" and "delete". No option offered for "download to device". Tried with and without a wi-fi connection.
App version 1.2.3 according to the Settings panel.