This is a new capabilty to me - Dashboard clearly seems to be considering it as an order number, for which a name makes no sense.
Did you try claiming just the serial number, without the name?
One thing to bear in mind with this - it's usually better to claim order numbers than individual serials / cloud IDs, as it claims all the serial numbers - and any included licensing - all in one go.
That does leave you to configure device names separately, of course...
On the issue you;re actually seeing, I'd suggest raising a case with Meraki Support. Please let us know how you get on!