Manage Subfolder Sync Randomly does nothing

## Describe the bug
I have a shared workspace.
I have multiple folders and subfolders, varying in size between 1gb to 200gb.
When I choose the option to manually sync subfolders, sometimes it will sync if i turn the check mark on. Sometimes it will say everything is synced but nothing syncs at all.

For example, I have a folder structure like: Design\Ads\2022 and Design\Ads\2023 (so on and so on for each year)

I choose to sync folder 2023 and it says 'synced' but nothing happens.

However, sometimes if I just create a new folder in the 2023 folder, it could be any empty folder, it starts to trigger some sort of refresh and it starts to sync.

I have tried manually forcing the sync, I have tried closing owncloud and opening it back up, but this issue still happens.

## Steps to reproduce
1. Open owncloud and select manual subfolder sync
2. Turn on a folder to sync
3. Wait for hours and hours and nothing syncs, even though the workspace says its synced

## Expected behavior
Should just start syncing after clicking check mark to sync folder.

## Setup
- Owncloud Infinite Scale 8.2, running in docker
- Owncloud desktop client on both mac and windows version 7.1

Start with the manual subfolder sync flow described in the reproduction steps, using ownCloud Infinite Scale 8.2 in Docker and the desktop client 7.1 on macOS or Windows. Reproduce selecting a folder such as Design\Ads\2023 and compare the reported synced state with whether files actually begin syncing; done means the selected folder reliably starts syncing after the checkbox is enabled.

Written by the indexing model from the issue text.