I am seeing some unexpected with a few parts when I connect a charging source and the battery is already fully charged.
The battery charger will report that it's charging but there is no current going into the battery. Both the Status/Control register and the STAT output indicate charging.
This condition can persist up to several hours before the part recovers and reports not charging.
Not all parts do this, but we have a few that act like this, so it's not just one defective part.