the devices just don't disappear. Check your org change logs. A device can be claimed into any number of organizations. "ownership" of a device is tied to the device being actually assigned/ deployed into a network.
The best practice is to claim the hardware and licenses via the Meraki sales order number and IMMEDIATELY assign the hardware into their corresponding network container. A device sitting idle in ORG inventory could be claimed into another org and actually assigned to a network outside of yours... the world is dark and full of terrors....