The way this bit me is that each time I upload, I create a playlist /new/{date}, and upload into it (this is so that I can do listening tests, tag checking, etc, and so that I can populate my /singles/{year}/ and /moods/*/ playlists without being distracted by already-processed tracks). I'd set /new/ to be ignore-as-child; this meant that everything I added was ignored...

Yes. When you play the root playlist, it ignores /new (because /new is marked ignore-as-child) but recurses into the other children of the root.

If that's not what you're saying -- if you're saying that children of /new get ignored when you play /new -- then that does sound like a bug.

Peter