Outlook 2016 - Syncing Documents from Sharepoint periodically doesnt work

Hallo

We are using Outlook 2016 and Sharepoint.

Outlook 2016 is successfully connected to a Sharepoint document library. Documents are synced INITIALLY when the connection is made, documents open fine.

However, no update is done when the Sharepoint content changes (e.g. documents are moved, or new folders are added).

Under "Progress" in the sync info of Outlook 2016, Sharepoint shows "completed" instantly.

Are there any settings we miss that prevent Outlook 2016 from regularly obtaining updates/latest files.

Kind regards

Nico