Actions has specific file extensions for each operative system, .acst for Mac and .actw for Windows.
This is made to avoid mixing shortcuts, as usually they are fairly different from Mac to PC.
With this is mind, one could want to load it anyway, to get at least all organization and icons ready, and maybe change the shortcuts manually.
Well, the workaround is easy: just change extension and give it back to Actions via Dropbox or iTunes.
(In case of Dropbox in the right folder, MacSets or WinSets)
Once loaded, you will see that the shortcut scheme has been preserved, only "option" is converted to "alt", and "command" is converted to the Windows button. (and viceversa)
Now remember to go and change the shourtcuts, or you may launch random commands unadvertedly.