Windows Hyper-v 2019 core - cannot register agent

Hi,

I'm using Acronis Cyber Cloud for server backups.

I have recently installed a Hyper-v 2019 core on a server and I want to register that host with Acronis cloud.

I have successfully installed the agent, tried to register with a token, but the portal says

"Check if the machine is online, connected to the network, and the agent setup program displays the registration window. If this is the case and the machine has not appeared under 'Devices', repeat the registration. To obtain a new code, click 'Show registration info' in the agent setup program that is running on the device. Alternatively, click 'Register the machine' in the setup program or Cyber Protect Monitor to directly register the machine."

I tried registering it using command line:

C:\Program Files\BackupClient\RegisterAgentTool>register_agent.exe -a https://eu-cloud.acronis.com --token BAE5-2136-41BD -o register -t cloud
level=err; message=akk error: Internal server error has occured (rc=15), http = {.httpCode = 500, .domain = AGENT_CORE, .code = UNKNOWN_CA}
Failed.
500

{
   "code" : "UNKNOWN_CA",
   "debug" :
   {
      "msg" : "ensure agent registration: test registration with agent manager: Post https://eu-cloud.acronis.com/api/agent_manager/v2/agent_registrations?d…: x509: certificate signed by unknown authority"
   },
   "domain" : "AGENT_CORE"
}
 

I tried to find a solution on https://kb.acronis.com, but couldn't find anything useful.

Anyone tried that in the past and knows any working solution? Please?

Thanks

Jerry