VPP: error 9609 when disassociate assets from user

VPP API v2 returns 9609 "Unable to find the registered user." when I disassociate assets from an existing user.

Repro step:

1. Create user

POST https://vpp.itunes.apple.com/mdm/v2/users/create

{
    "users": [
        {
            "clientUserId": "client-1",
            "managedAppleId": "valid managed apple id"
        }
    ]
}

=> user is associated

2. Retire user

POST https://vpp.itunes.apple.com/mdm/v2/users/retire

{
    "users": [
        {
            "clientUserId": "client-1"
        }
    ]
}

=> user is retired

3. Recreate user with the same clientUserId

POST https://vpp.itunes.apple.com/mdm/v2/users/create

{
    "users": [
        {
            "clientUserId": "client-1",
            "managedAppleId": "valid managed apple id"
        }
    ]
}

=> user is associated

4. Associate asset

POST https://vpp.itunes.apple.com/mdm/v2/assets/associate

{
    "assets": [
      {
        "adamId": "408709785"
      }
    ],
     "clientUserIds": [
      "client-1"
    ]
}

=> asset associated

5. Disassociate asset

POST https://vpp.itunes.apple.com/mdm/v2/assets/disassociate

{
    "assets": [
      {
        "adamId": "408709785"
      }
    ],
     "clientUserIds": [
      "client-1"
    ]
}

=> {"errorNumber":9609,"errorMessage":"Unable to find the registered user."}

Notes

• associate API works fine with the same payload.
• disassociate work with v1 API.