How can I get ALT key to register as a keybind on Mac with crossover?

Are there any Mac users out there who know how I can make use of the 'Alt' key for a keybind? Supposedly, 'option' is the mac version of the alt key, but it doesn't work.

Sometimes, when I create a new keybind using 'Cmd - X' , it registers as 'Alt-X'. When I test the keys, the thing I mapped it too works when I press 'ctrl-X' or 'Cmd-X'. When I go back into the keybinding menu, it has changed to read 'ctrl-x'. At no point does the option key work to bind anything.

Has anyone had any success getting an Alt keybind to work on a mac?