This is a very common occurrence for shipping.
When large amounts of items are shipped together, they are often loaded onto containers. Items are then automatically linked to the individual container they are travelling in and this will automatically update during the journey.
Sometimes, if an item misses a scan going onto the larger container, it can show as not moving when it is in fact travelling without an issue.
This issue normally resolves itself when the container makes its arrival into the couriers' next facility where the items are off loaded and reloaded onto another container.