Link to LP bug: Drag and drop sometimes doesn't do anything. I can select (a) file(s) and move them to another thunar window or the desktop, but upon releasing the mouse button nothing happens besides the animations (of the selected files flying back to its origin) that occurs when drag and drop is not possible because of legitimate reasons (no permissions, other app doesn't support drag and drop). Strangely this behavior isn't always consistent system-wide. For example, I noticed drag and drop not functioning with an image file from a thunar window to Gimp, but it did at this time between two folders. When drag and drop between two thunar windows isn't working, neither is it within one window (from the active map to a favorite map in the side-bar) I noticed this behavior on my previous install with was an upgrade from 13.10 to 14.04 (32-bit) as well.
Sorry for the late reply ! For Other-App to thunar drag & drop problems there are already some open issues. For thunar to thunar, I did not see any so far. Could you, if possible, tar the folder for which the problem exists, so that we possibly can reproduce the scenario ? Which Thunar-View did you use ?
Closing, reopen if this is still a issue with recent versions.