Newly created files are not downloaded when syncing a folder

### Steps to reproduce
1. Sync an existing folder. All files are downloaded.
2. Create a new file on the server.
3. The file shows up in the android app, but will not be synced.

### Expected behaviour
- Newly created files should be synced, too

### Environment data
Android version: 11

Device model: Oneplus One

Stock or customized system: LineageOS

Nextcloud app version: 3.18.1

Nextcloud server version: 23