Hello @Malimber,
@MartinLL and @DarrenOC are correct. The device move process between organizations can take up to an hour or so to fully sync on the backend (and potentially even several hours if the device move is between organizations in different regions.. i.e. moving a device from a .com org to a .ca org)
If you are still receiving the already claimed message after waiting this time period, please open a support case (detailing the serial number of the device in question), so that the backend sync can be looked into at a deeper level.
To open a support case via the dashboard, please navigate to (?) > Get Help & Cases > Pick a Tile to Contact Support > Submit a case or by following the steps provided in the Contact Cisco Meraki Support document here.
Best,
Feli
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