Bizarre problem with NextCloud syncing on TrueNAS

Hello, I have Nextcloud installed as a TrueNAS jail and I’m having a bizarre problem with syncing.

Basically I have an SMB share which I’ve mounted in NC as external storage. This allows me to work on my local computer with the network drive, and also allows users to sync and work remotely.

However, something strange has started happening recently. When a user overwrites a file and syncs it using the desktop client, it updates in the web interface but doesn’t update in the SMB share. If I download their file from the web interface, it shows the correct version. But if I just navigate to the file in Windows, it shows the old version BEFORE it was overwritten.

I don’t know how this is possible. There must be some cache of the old file that’s taking precedence over the updated one, right?