File modified with excel not synchronized

### Actual behaviour
- A file already on the server, opened with excel android, modified and saved is not synchronized

### Expected behaviour
- It should be automatically synchronized

### Steps to reproduce
1- create a file on pc, it is synchronized with the server
2- open it : Nextcloud / navigate to file / open / choose excel as editor
3- modify the file
4- press "back", in excel top bar it is written as "saved"
5- wait and the **file is never synchronized**
**or** ( see the step's numbers, That's important )
5- in nextcloud file browser, click "synchronize" menu of the excel file. **It is correctly synchronized**
**or**
2- in nextcloud file browser, click "set available offline" (sorry I don't kown the exact english translation) menu of the excel file.
3- open It
4- modify the file
5- press "back", in excel top bar it is written as "saved"
6- wait and the **file is correctly synchronized**

### Environment data
Android version: 8.0.0

Device model: Galaxy S9

Stock or customized system: stock

Nextcloud app version: 3.3.1

Nextcloud server version: 14.0.3

### Logs
#### Web server error log
``` N/A
Insert your webserver log here
``` N/A

#### Nextcloud log (data/nextcloud.log)
```
Insert your Nextcloud log here
```
**NOTE:** Be super sure to remove sensitive data like passwords, note that everybody can look here! You can use the Issue Template application to prefill some of the required information: https://apps.nextcloud.com/apps/issuetemplate