Nero tags

Is there any way to write an Action to delete the Nero "Encoded By" tag in m4a files? I've had no luck so far.

Have you tried the advice in this thread?
action to delete tags

Yes, that works on every unwanted tag except "encoded by," "cdec" and "ITUNSMPB." I've been able to write a separate Action removing those last two, but for some reason "encoded by" remains.

Is it possible to delete it in the Extended Tags dialogue (Alt-T)?
If so, please show us exactly what you have written in your action as I would then suspect that it is a problem of too many or too few blanks or such stuff.

Hello

I'm not sure if this information is in any way relevant
and I hope I am not stating the obvious.

When tagging MP4 files containing a TV series
I noticed that MP4-Nero had appeared in the field.

I had inserted 1-01, 1-02, 1-03, etc. in the field to denote the various episodes.
When I deleted these entries with - or modified them to 101, 102, etc. -
the field reverted to just MP4.

Best regards
Ray

Your signature still shows a 2.4 version.
Here is a quote from the MP3tag program page:
https://www.mp3tag.de/en/#formats

2017-08-25
Mp3tag v2.84 — This version adds support for Nero-style chapter tags and adds two cover-only Tag Sources to import album covers via Discogs.

So there has happened something with the nero style chapters (i.e. support).
It could be that you see the outcome of if.