[Bug]: Nextcloud Sync Folder Inconsistency

### ⚠️ Before submitting, please verify the following: ⚠️

- [x] This is a **bug**, not a question or a configuration issue.
- [x] This issue is **not** already reported on Github (I've searched it).
- [x] Nextcloud Server and Desktop Client are **up to date**. See [Server Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) and [Desktop Releases](https://nextcloud.com/install/#install-clients) for supported versions.
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/)

### Bug description

Summary

Nextcloud client fails to display existing sync folder while preventing the addition of a new one, claiming it's already in use.

Removing the connection to the server and trying to recreate it, lead to the same issue.

The sync folder disapeared in one of the two defined connections (to different server and with different local sync folder), while the other connection did not get affected.
When comparing the current nextcloud.cfg (clientVersion=3.16.2 (build 20250319)) with the previous (clientVersion=3.16.1 (build 20250313)) I found, that several entries have been moved to another row or maybe even totaly deleted. e.g.( "1\networkProxySetting=0" or "1\serverHasValidSubscription=false"). More details I cannot provide.

### Steps to reproduce

Open Nextcloud client
Observe that no sync folder is displayed in the client interface
Attempt to add a new sync folder
Receive error message stating the folder cannot be used as it's already a sync folder

### Expected behavior

The client should either:
Display the existing sync folder correctly
Allow the addition of a new sync folder if no active folder is detected

### Which files are affected by this bug

nextcloud.cfg

### Operating system

Windows

### Which version of the operating system you are running.

Windows 11 Pro

### Package

Official Windows MSI

### Nextcloud Server version

affected connetion: Nextcloud Hub 9 (unknown) / working connection: Nextcloud Hub 9 (30.0.8)

### Nextcloud Desktop Client version

Nextcloud Desktop-Client Version 3.16.2 (Windows)

### Is this bug present after an update or on a fresh install?

Fresh desktop client install

### Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

### Are you using an external user-backend?

- [ ] Default internal user-backend
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other

### Nextcloud Server logs

```shell
I don't have access to detailed server information or any Server logs.
```

### Additional info


Desktop Client Logs: Debug Archive contains personal data, cannot provide this.