Final Cut Pro 3: Clip Appears Black When Applying Round Rectangle Matte

This document describes an issue with using masks with a round rectangle shape in Final Cut Pro 3 for Mac OS X.
Symptom

After applying a matte with a mask shape of "round rectangle", the clip appears black after rendering.

Solution

Use a different shaped mask.

OR

Use Final Cut Pro 3 for Mac OS 9.
Published Date: Feb 18, 2012