Solving a Mystery- id3 Tag titles of MP3's on car stereo unit

Hi all. Need some assistance please. So I have a library of 2800 songs.
Out of all of those, 15 were giving me trouble… Related to a car stereo unit (aftermarket CD/USB player deck-single DIN-with method of play here being USB) - displaying text/id3 tags. But ONLY 15 songs, and not long file named ones or anything like that, it was very random with truly no rhyme or reason!
The initial MP3 files had the correct & proper id3v1 and id3v2 tags - and that was displayed on all sources (such as this particular car stereo unit.)

But, the files had some silence at the beginning & end that I didn’t like, or other various small things, so I chose to edit a large portion of them. When I edited them (ie cut beginning or end a bit, modify in any way) – they were converted to/saved as a WAV… I saved these WAV files, and ended up reusing them later… But of course I needed to recode the WAV back to MP3, and here is where the problem began.
Initially I Re-coded to a 192 bitrate, then later tried at 128 bitrate - but at both of those bitrates, the ARTIST ID section showed “no name” on my car stereo (song title was there.)

ALL id3tags in winamp, windows explorer, tag&rename program were present, correct, & issue free – AS WELL AS two separate ipod units! Only the car stereo gave me this issue w these songs!!
Now further, when I encoded those SAME ORIGINAL WAV’s at 320 bitrate instead – the artist DID NOW display on the car stereo, BUT, the song title, after it was finished, had a P and a lot of underscores after it… Every single song had this occur/was the exact same!!
Again I went back & double checked – ALL id3tags in winamp, windows explorer, tag&rename program were correct – AS WELL AS those two separate ipod units. THERE IS NO P AND UNDERSCORES ANYWHERE IN THE FILE NAME, NOR EITHER ID3 TAG…!! Again, Only the car stereo deck was giving me this issue w these songs and the P & underscores!!

Then, I tried two other, completely different programs for encoding… Both programs still from those original WAV files. Both had the EXACT same results (ie 192 and 128 bitrates showed “no name” in ARTIST section on car stereo but nowhere else, 320 bitrate had the infamous P & underscores after Song titles.)

Finally, I tried a third program, still from the exact same original WAV’s mind you – and this one worked like a charm!! Encoded at 192 bitrate, the program did its job and did exactly what I wanted it to do…! No issues, no problems… So finally I accomplished that task but this was certainly quite perplexing, and I’m just curious as to why!!
Any suggestions why this occurred in this way??? Thanks so much in advance!!

There are ID3v1 and ID3v2 tags.

Does tag&rename allow you to check/edit them both?

Yes, I’m aware - thanks for that suggestion.
Yes the program does, I had checked both id3v1 and v2 in ALL instances – and they were correct with no issues…

Have you tried completely removing the tags and starting over?

…Audacity doesn’t handle/support all tags (or all tag formats) perfectly, and in-general (not just Audacity) tagging for WAV files is not well-standardized or well-supported.

Since the original MP3s were OK, you can try trimming them with [u]MP3direct Cut[/u]. MP3directCut doesn’t decompress & re-compress so you don’t get lossy-to-lossy generation loss and it doesn’t have to re-write the tags.

Good info! I’ve not tried that program, thanks for the suggestion - I will check it out!