You have a machine with installed Acronis Agent registered in Acronis Cyber Cloud. You want to re-register this machine to another tenant and use this guide: Registering backup client manually.
When following the guide, you provide incorrect credentials, token or data center and the command fails. After the failure, the Agent is unregistered from its current tenant (is not listed in Devices).
This issue has been fixed in Acronis Cyber Cloud 20.11.
Workaround for earlier builds: run the command once again with correct values; the Agent will be registered in the new tenant.