Two-way sync does not synchronize files in subfolders; only main folder files are synced

### ⚠️ Before posting ⚠️

- [x] This is a **bug**, not a question or an enhancement.
- [x] I've [searched for similar issues](https://github.com/nextcloud/android/issues) and didn't find a duplicate.
- [x] I've written a clear and descriptive title for this issue, not just "Bug" or "Crash".
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Steps to reproduce

Delete all Caches/Data for Nextcloud Android App
Deinstall Nextcloud Android App
Reinstall from Google Play Store
Connect App over App Passwrod on Self Hosted Nextcloud Server
[Inside App] Activate 2-way Sync over Menu -> Settings -> Internal 2-way Sync
[Inside App] On File Overview: Selected one Folder (With Sub Folders) -> Open Details -> Select Syncronisation
[Inside App] On File Overview: Mark Same Folder and start first syncronisation bei opening the 3-Points Menu and pressing "Synchronisieren" (using de version)

### Expected behaviour

The hole folder including all of the sub folders and files has to be synchronized. There are only mp3 and m3u files in there. The main folder has a total size of 2.7GB.

### Actual behaviour

Only the *.m3u files are synchronized, directly under the main folder. But none of the underlying folder, which containing all of the *.mp3 files.

### Android version

16 ( Build: BP2A.250605.031.A5 )

### Device brand and model

Google Pixel 6

### Stock or custom OS?

Stock

### Nextcloud android app version

3.32.3

### Nextcloud server version

31.0.7

### Using a reverse proxy?

No

### Android logs

_No response_

### Server error logs

```bash
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/ HTTP/1.1" 207 1326 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Crosing.m3u HTTP/1.1" 207 1408 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Dreaming.m3u HTTP/1.1" 207 1400 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Rausch.m3u HTTP/1.1" 207 1407 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/Schleichfahrt.m3u HTTP/1.1" 207 1421 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
[remote-ip] - [myuser] [05/Sep/2025:15:05:48 +0200] "PROPFIND /remote.php/dav/files/[myuser]/Music/ HTTP/1.1" 207 13028 "-" "Mozilla/5.0 (Android) Nextcloud-android/3.32.3"
```

### Additional information

_No response_