The one that's missing is probably the same one you have selected in the last screenshot, because it is missing the Artist tag. If you add an artist tag of UFO, I bet it will be included.
As for your earlier screenshot, where there is no UFO in the Artists in the main panel, do you have that grouped by Artist or Album Artist? What is the Album Artist for these tracks?
Agreed about the meta tag missing, but that was my entire point: We would never even see the file unless we were aware of the files in the first place. That's why I posted another thread asking to use a "sort" by directory structure in the main file window. e.g., sure, we could add missing "sort" parameters to the meta data, but how would we know what files were missing that data in the first place?
In Library>Music, using both Artist and Album Artist, the missing file is still not there.
Another example of why having a sort by directory option is a good idea is that I have thousands of songs that I "saved" from streams using the Winamp and AIMP "capture" option--to save each song from a stream as an mp3 file. This option, if you were wondering, does not record the file then creates new mp3 for it. it actually captures the mp3 at whatever bit-rate is streaming. So instead of getting a re-compressed mp3 (shjitty) you get teh original file that was streaming. (I've also requested thta option for MB, as stated, both Winamp and AIMP have that option).
Anyway, in order to see what files are actually missing meta data, and thus are no showing up on sort functions, the only way I see to get around that is to have a sort option that somehow sorts by directory, so that you could see waht files are missing necessary meta data:
e.g.,
Sort header
Directory | Artist | etc
This is important: Even when I go to the parent directory and select "C:\MyMusic\
MB won't find the missing files. I have to click on the specific directory in order for it to show ALL files in that directory.
e.g.
C:\MyMusic
Shows all files in all sub-directories in the man window, but misses files w/o necessary meta data. (It shouldn't do that actually, at least not for the "computer" file browsing option. To me, it should show all of the directors (and any files not in sub-directories) below that directory. Or, it should really show ALL FILES, even those with missing meta tags.
C:\MyMusic\UFO
NOW we see all of the files, including the missing file (No artist name).