"Unlike categorization by effects type, there is no way to see categorization by intended source on the list menu page in the PROGRAM area. However, as we will see shortly, categorization by source becomes very handy once you start searching for programs. When you save your own programs or your own tweaks of factory programs, you can assign source "flags" yourself on the sources menu page in the PROGRAM area. Here the Vocals and Special FX flags are on. "
So, you'll have to save your own tweaks of the factory presets and add whatever source flags you like to use the "Source" filtering.