Changed tags not changed when loaded on iPod

In short, I have a few thousand mp3's of audio talks pertaining to my trade. I have been using mp3tag to edit the tags for quite awhile.

For awhile now I have been noticing that when I edit the tag of an mp3 file that had a preexisting tag, when I load it onto my iPod, the tags are not what I entered, but are the original tags.

This is frustrating. I have spend hours of my time editing the tags to what I would like them to be, and I can't figure out why this is happening. If anyone has some insight on a setting or something I am overlooking, any feedback is appreciated!

Thank you in advance!

I don't know where the iPod gets the tag data. But iTunes has to be forced to re-read a file that it already has read.
So check iTunes to see the data there and find out if it gets updated or not.
If not, you either have to apply one of the updating scripts that the iTunes community provides or delete the files from iTunes and re-import them.

If all that does not help: check which tag types you read and write with MP3tag.
You should read and delete all, but write only Id3V1&V2.
See Tools>Options>Tags>Mpgeg for the settings.

The way I have iTunes configured, the only files it sees are the ones I download through it. The folder I keep all my audio files I set to not be included in the iTunes Library. Even the few podcasts I download through iTunes I move the files to another non-iTunes library folder, rename them, sometimes convert them into a different bit rate, then I change the tags through mp3tag, then drag and drop them onto my iPod, so I'd imagine they'd have to be reread anyway.

I am really picky about having all my audio files named and tagged consistently over my own personal organizational system so I know what I have and can find it easily. It drives me bonkers when I look at someone else's files and they're all named and tagged differently.

I checked the mp3tag settings and the tag options were already set how you suggested. It boggles my mind. I look at the audio files through the file explorer, the tags are what I set them as, I load them on my iPod, some of them show the old tags, some of them show the tags I set, some of them don't seem to be anywhere when I look at them by album or artist but when I look at the playlist I put them in they're there and when played show the tags I set.

Does anything really help?
I would suggest that you totally clear the iPod.
Then import the files again.

You do not say anything about the fields that you fill.
You should fill ALBUMARTIST, ARTIST, TITLE, ALBUM, TRACK, YEAR, possibly the cover.

I am not sure what you mean by

It is usually not enough to modify the filename as this should not be important if you have filled the tag fields.