Why can I no longer export alpha channels in the new FCPX update (10.0.6)?

Question

While the new update is rich with new goodies- I am having some issues doing some things.  My main concern is the inability to export alpha channels in the 10.0.6 updated version of FCPX.
I followed the following steps, same as before the update.
I used the Keying effect to remove the greenscreen and did some cleanup using the "sample color" refining tool.
I cropped and resized the clip so that the actor is the correct size for my clip.
Now it looks great in FCPX, except that I now need to put that footage into Motion 5 and do some motion tracking and match move.
I export the keyed clip as Apple Pro Res 4444
Now when I import that file into Motion 5 everything that is supposed to be transparant is black! 
Is there an additional setting in the new version that I need to fix in order to export alphas?  Is there a new way to do it?
I am operating Mountain Lion, OSX Version 10.8.2 with a 2.66 GHz Quad-Core Intel Xeon processor. 
Thank you so much!  This is a key element in almost all the projects I do and now I am stuck!

Answer 1

You got me curious so had to test and validate some of the above, forgive me if I go a little OT in the process.
Have you set your background to checkerboard, I find psycologically this makes a difference, though in exporting it does not...
screen grab below, from 422 timeline, showing original, exported 444 and then imported file comp'd in and scaled down for differentiation in FCPX, note that the project render parameter is actually set to 422 NOT 444 as fox_m suggested, it still works.
This one below shows the above scenario exported 444, with background set to black in pref's, note the overlap showing transparency, again in FCPX. This is purely to illustrate that the checkerboard and black backgrounds are not relevant, only that the 444 on export is relevant.
Hopefully this illustrates that cropping and 444 exports are working.
Tony