iTunes not consistently renaming imported MP3 files

I'm running iTunes 12.3.2 on several systems (all Windows 10, both 32- and 64-bit). I've noted some slightly odd behavior when adding Amazon-purchased mp3 media to my iTunes library. Since I have both the Copy ... and Keep Organized ... options enabled in Edit > Preferences > Advanced the expected result is that iTunes should rename files as they are copied, following the patterns:

• <track number> <track name>.mp3 (single disc albums)
• <disc number>-<track number> <track name>.mp3 (multi disc albums)

My standard practice is, if necessary, to update the mp3 files' metadata outside iTunes using Foobar 2000 (since this provides much better bulk editing tools than iTunes), typically I'm making changes such as:

• correcting Artist, Album and Track names if they don't match my standard conventions (or are just plain wrong)
• adjusting Artist attribution so that tracks that feature guest artists have these in the Artist value rather than appended to the track name
• removing irritating suffixes like "(Live)", "(Remastered)", "(Album version)" that Amazon / media companies add to their supplied track metadata
• verifying and if necessary changing the mp3 tagging version to be ID3v2.3 and removing any redundant tag versions

Therefore, I'd expect iTunes to be consistently renaming files during the import process to match the metadata values. However, I happened to open up a File Explorer window and browse to the folder created by iTunes for a new import. My library's on an external drive, so the pattern for folder names is:

<drive>:\\iTunes\iTunes Media\Music\<artist name>\<album title>

What I'm seeing here is one of two conditions:

• the file names after the copy operation are the same as downloaded from Amazon, i.e., haven't been updated to reflect the metadata changes, or
• are a mix of the original Amazon file names and the correct iTunes-generated names

Further checking has shown that subsequent updates in iTunes (e.g., modifying the associated artwork) does then correct all the file names to match the expected pattern as determined by the "Keep Organized ..." setting.

In some respects, I actually don't care about this as I generally don't worry about how iTunes stores/names media files as long as it maintains the integrity of my library. However, this may be associated with some other symptoms (most notably the oft-reported issues with albums not grouping properly) that suggest that recent versions of iTunes have had issues with evaluation of metadata-based rules.

Anyone else seem the same thing? I think that this should be reported as a bug, but I'd prefer to verify that this isn't a quirk associated with my library (although I have multiple PCs running iTunes they are all using copies of the same library).