I forgot to include this in the above message:
I'm running a folder-based library.
I have 361923 tracks on a single internal HDD.
I'm on beaTunes 5.1.11-snapshot, built on Oct 11 2018
JVM: JavaHotSpot 64-bit server VM Verison 1.8.0_181 (25.181-b13)
OS: Windows 188.8.131.52, amd64
Memory: 92m-4096m, currently 1931m (47%) which fluctuates as you know
When I analyze a group of new tracks, for fingerprints, both the boxes are checked ("Take fingerprint" and "Submit fingerprint"). For BPM, only the "Estimate BPM" box is checked, and the Range is "Automatic". Also, no other Analysis boxes are checked (no "danceability", no "mood", etc.).
When I re-analyze a group of tracks that didn't get a BPM value written to them, the only difference is I uncheck the "Take fingerprint" box. Every time I've done this so far, every track that didn't get a BPM the first time around, gets one the second time around.
And these are, definitely, tracks that were subjected to analysis the first time. Typically, I'll download one or more CDs worth of tunes, scan them into my other player's database, (sometimes) clean up the tags there to my satisfaction*, (usually) run a Replay Gain analysis there on the new tracks**, scan the tracks into beaTunes for the first time, skip the "Inspect" step, and do the Analyze step with the options as described above. When the analysis is done [and there is virtually never an error], I go back into my other player, rescan the music folders to bring in the BPM values. That is when I see that some tracks got a BPM added and some didn't. Then I go back into beaTunes and see, yes, those same tracks don't have a BPM in beaTunes for whatever reason. Then I re-analyze the selected tracks as described above.
These are almost always mp3 files. In fact, I think every file I've had this problem with is mp3. I seldom deal with other music file types (m4a, flac, ogg, ape, etc).
*- Sometimes I clean up the tags before the initial scan. "Clean up" to me means fixing or adding the song title, artist name, album artist name, album name, track number, year, composer, and genre. Sometimes it gets done much later. Sometimes (often) it gets done in pieces. Tag clean-up/enhancement is a never-ending process, it seems.
**- I know beaTunes can do the Replay Gain analysis also. For consistency, I always do the volume analysis in my other player (MediaMonkey) because I've used that same player for years. That player, however, doesn't have a BPM analysis module, nor does it have some of the other great beaTunes features. Yes, it does take some self-discipline to make sure the two apps don't mess things up for each other or in the underlying tracks themselves. I believe I am duly careful.