Automation Action: SharePoint - Update Item In List
Updates an item within a SharePoint list. By providing the relevant query criteria, the first matching item will be updated. If no query fields are provided then a new list item will be created. The value returned will be the ID of the item updated or created.
By default not all query fields are shown - this is because SharePoint doesn't allow querying on all fields and therefore only the known good fields are initially shown. You can however show all fields and test if querying upon them works under your circumstances.
The "Site" field should be provided in the following format: mysite.sharepoint.com