# M4A not recognised as stem file in Traktor

**URL:** https://community.mp3tag.de/t/m4a-not-recognised-as-stem-file-in-traktor/70869
**Category:** Mac
**Created:** [March 13, 2026, 9:59am UTC](https://community.mp3tag.de/t/m4a-not-recognised-as-stem-file-in-traktor/70869 "2026-03-13T09:59:05Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![xavius](https://community.mp3tag.de/user_avatar/community.mp3tag.de/xavius/32/8750_2.png) [@xavius](https://community.mp3tag.de/u/xavius)
#### Post date: [March 13, 2026, 9:59am UTC](https://community.mp3tag.de/t/m4a-not-recognised-as-stem-file-in-traktor/70869/1 "2026-03-13T09:59:05Z")

</div>

Hello,

I’m experiencing an issue when editing Traktor Pro 4 stem files with MP3Tag.

Situation:

I generate stems using NUO-Stems.

The files are correctly recognized as Stem files in Traktor.

To test this:

I create a stem file.

I make a copy of the file.

Both files are recognized as stems in Traktor.

I run an MP3Tag Action Group on the copied file.

After saving, Traktor no longer recognizes the file as a stem file (it loads as a normal track).

Notes

Some basic edits do not break stem recognition, for example:

changing the TITLE

editing COMMENT or ALBUM

However, when running my full Action Group, the file loses stem recognition.

The action group mostly does:

tag formatting (YEAR, TRACK, LABEL, GENRE)

many Replace "\_ALL" cleanup rules

Camelot key conversion

Case conversion "\_ALL": Mixed Case

clearing some tags

renaming the file %ARTIST% - %TITLE%

Question

Is it possible that one of these actions causes MP3Tag to rewrite or remove non-standard metadata chunks in the file container?

Traktor stem files contain extra internal metadata that identifies them as stems, so I suspect something may be modifying that.

Can someone check what is being edited so i can remove/change that?

Files can be found here: [Stems\_check – Google&nbsp;Drive](https://drive.google.com/drive/folders/1L3MDrdgOE8TewVUZYOxlo-qzDuMINSHB?usp=share_link)

---

<div class="post-metadata">

### Author: ![Florian](https://community.mp3tag.de/user_avatar/community.mp3tag.de/florian/32/5759_2.png) [@Florian](https://community.mp3tag.de/u/Florian)
#### Post date: [March 13, 2026, 2:14pm UTC](https://community.mp3tag.de/t/m4a-not-recognised-as-stem-file-in-traktor/70869/2 "2026-03-13T14:14:08Z")

</div>

Can you try with the option **Settings → Advanced → Reuse unmodified MP4 atoms** enabled?

 ![image](https://community.mp3tag.de/uploads/default/original/3X/8/4/844892fa3afb8ebaa9a58eaf98d9f72f8af64135.jpeg)

---

<div class="post-metadata">

### Author: ![system](https://community.mp3tag.de/uploads/default/original/2X/c/ce7035d426cb755a7916793326d23b465222a407.png) [@system](https://community.mp3tag.de/u/system)
#### Post date: [March 20, 2026, 2:15pm UTC](https://community.mp3tag.de/t/m4a-not-recognised-as-stem-file-in-traktor/70869/3 "2026-03-20T14:15:03Z")

</div>

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.