It is now possible to generate proxy media for matte clips inside a Multi-Channel clip and Matte Container. When generating proxies, only the matte defined in the Multi-Channel clip & Matte Container (the S track) is generated. If you enable the Render/Proxy Options/All option, all mattes located inside the Multi-Channel clip/Matte Container are generated, including any shots located on any timeline layers of the primary video track.
To automatically generate matte proxies for the secondary track (S):
To generate proxies for all mattes