If you have altered any metadata for iTunes Store purchases from their original values then you may be seeing the store metadata instead of your own. If you think that could be an issue then try the following:
Go to iTunes > Preferences > Store and turn off
- Show iTunes in the Cloud purchases
- Share details about your library with Apple
On any iOS device go to Settings > Music and turn off
Show All Music
Close and reopen iTunes and/or reset the device and you should see your version of the metadata for each track rather than the original store data. Alternatively my script UpdateTagInfo will force iTunes to read the current data from the tags.
If mp3 files are involved then the issue could be multiple embedded tags where one gets updated when you make a change, but iTunes or any device may later read back unchanged data from another. A workaround in iTunes is to use right-click context menu Convert ID3 Tags... > None a few times to remove all existing tags and then Convert ID3 Tags... > v2.3 to build a fresh tag with the information still held in the iTunes database. I've read in the past that iTunes isn't fully compliant with the v2.4 spec. although this may no longer be the case, however support for v2.3 is widespread so I would suggest using v2.3 over v2.4. Note this process removes any embedded artwork.
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