Exports From FCP Fail in QuickClusters

Surprise! From Apple's TA1099 Knowledge Base article.

You will not be able to successfully export from Final Cut Pro using Compressor if your computer is set up as a Compressor QuickCluster, or a "Virtual Cluster." If you attempt to send an item from Final Cut Pro to Compressor in such a case, some segments in the job may report "Failed" and processing of the batch will not complete successfully.

What can you do?

You can work around this issue by first exporting a self-contained movie from Final Cut Pro. You can then use a QuickCluster in Compressor to transcode that self-contained movie.

Alternately, you can export from Final Cut Pro directly using Compressor, but use a single-service instance of Compressor instead of a QuickCluster.