Issue with Endpoint Migration via API between two tenants

Hi,
I am trying to migrate an endpoint from one tenant to another, each request I have sent sits pending then fails after a few minutes.

on the sending Tenant I am getting 
'reason': 'Error (400)'

On the receiving Tenant I am getting 
'reason': 'Endpoint cannot be migrated with the current version. Please update when available.'

On the dashboard I can see an error of "Device failed to register with new account <ACCOUNT ID>. It continues to be managed by this account."
Has anyone encounter this issue, how did you deal with it, or is there extra steps that I may have missed.

Thanks in advance.