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

Reimport the exported file and check the alpha channel in the FCP inspector.

Go out to the project level ; in the inspector, click on the wrench icon at the bottom of the palette and in the dropdown dialog make sure your project is ProRes 4444 and NOT ProRes 422 for the "Render Format" (bottom line). Even if you export as 4444, if your project is not set up for the transparency, FCPX will export what you think is transparency as black background. I think everybody assumes projects are automatically set up as 4444 (that's actually Motion). Unless you make that custom decision, FCPX sets up the default as 422 (not even HQ!).

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

Another thought, what do you have the alpha set to in Motion?

Tony

Tony. This is interesting. I like the "checkerboard" preference. Reminds me that I'm dealing with a key layer. Q: Now, obviously, this is a visual adjustment. It does not affect the key (alpha channel) itself?

You can export proxy files, but you probably don't want to. It'll be low res and poor quality.

If you need transparency, only two codecs can be used: ProRes 4444 or Animation, and you can't export Animation from FCPX, but you can from Motion 4 (and some other apps). That said: you probably will not want the Proxy footage FCPX exports (1/4 resolution) for any project in Motion. That's not to be confused (and I'm sure it often is) with ProRes Proxy, which IS a viable codec to use in Motion projects. The difference is: ProRes Proxy is a full resolution codec (with a decently high *bandwidth*) that uses higher compression than its ProRes siblings; FCPX proxy footage uses a ProRes codec, but the video resolution is decreased by 1/2 for each dimension (1080 becomes 960x540) and therefore 1/2 x 1/2 decrease on both dimensions is a total of 1/4 of the total pixels used to represent a frame... not what you'd want for a "finished" Motion project.

HTH