An incident on an old SharePoint 2007 reminded me of 2 workflow-related issues affecting SharePoint when the column “Assigned To” is configured to allow multiple selections.
While one of them is fixed from SharePoint 2010, the other persists until SharePoint 2013.
Here are the matching KB Articles:
- MS KB Article: Approval workflow processing does not complete and assignments are not made
- MS KB Article: Three-state workflow does not run when a “People or Group” column allows multiple selections in SharePoint
Thanks to @jlebutte and MS Support for their help!