Yes. That's correct. And, yes, it makes no sense whatsoever.
Double clicking on a song from the top-level Audio View Scheme (unfiltered) works differently than double clicking on the same song when the list is sub-filtered (via panes, search, child view schemes, or whatever). (Differently in that it plays in one case and doesn't in the other.)
I should mention, my Double Click settings are set to Send to Playing Now (if has Display), which doesn't apply for music, and Play All. About the only thing I could think of was that it has something to do with the number of files added to playing now. If I double click to play a file on that machine from the top-level, it adds about 16,500 audio files to playing now. When I sub-filter the list, obviously the number is different (and lower). I didn't have a bunch of time but I did try with one huge sub-filtered view scheme I have (called "Everything But the Sink" which simply excludes audiobooks, classical, podcasts, interviews, and other similar things) which has over 12,000 files in it and that worked fine.
DSP Studio is completely disabled on that machine (no Volume Leveling or EQ or anything).
I didn't think to try Right-Click --> Play from the top-level (which would only add the one file), unfortunately, so I don't know the answer to that question.
EDIT: I really, really think the DSP is all disabled, but I will check that when I get home. Perhaps that is the culprit, though wouldn't the MC spectrometers still work even if it was "volume leveling" everything away... Or do those show "actual" output, post-DSP?