Inviting participant fails with error 500 resultInfo if replacesCallId is set

I'm trying to invite a participant to a new call without them being placed on-hold, using the C# Graph SDK.

My Request looks like this:

            await _client.Communications.Calls["0b206000-3836-4567-bd3c-1ac2ac394ac3"].Participants.Invite(new[]
            {
                new InvitationParticipantInfo
                {
                    ReplacesCallId = "ab1f5f00-7b34-4a08-98d0-1259d8a6cb91",
                    Identity = new IdentitySet
                    {
                        User = new UserIdentity { Id = "449626fd-5f81-4ced-9d61-774c904e8c43" }
                    }
                }
            }).Request().PostAsync(cancellationToken);

The comms notification arrives with this result:

{
    "@odata.type": "#microsoft.graph.commsNotifications",
    "value": [
        {
            "@odata.type": "#microsoft.graph.commsNotification",
            "changeType": "deleted",
            "resource": "/app/calls/0b206000-3836-4567-bd3c-1ac2ac394ac3/operations/773efa4c-0232-4ccb-bd55-45611a20b724",
            "resourceUrl": "/communications/calls/0b206000-3836-4567-bd3c-1ac2ac394ac3/operations/773efa4c-0232-4ccb-bd55-45611a20b724",
            "resourceData": {
                "@odata.type": "#microsoft.graph.inviteParticipantsOperation",
                "participants": [
                    {
                        "@odata.type": "#microsoft.graph.invitationParticipantInfo",
                        "identity": {
                            "@odata.type": "#microsoft.graph.identitySet",
                            "user": {
                                "@odata.type": "#microsoft.graph.identity",
                                "id": "449626fd-5f81-4ced-9d61-774c904e8c43",
                                "tenantId": "3e9638b4-e59e-49ac-bd66-ab3b59d45ee5"
                            }
                        },
                        "replacesCallId": "ab1f5f00-7b34-4a08-98d0-1259d8a6cb91",
                        "participantId": "5717b7aa-31dd-44f4-8a55-722d478a2677"
                    }
                ],
                "status": "failed",
                "resultInfo": {
                    "@odata.type": "#microsoft.graph.resultInfo",
                    "code": 500,
                    "subcode": 9999,
                    "message": "addParticipants failed for participant 8:orgid:449626fd-5f81-4ced-9d61-774c904e8c43. Underlying reason: Http Call Notification Failure.. DiagCode: 500#10046."
                },
                "id": "773efa4c-0232-4ccb-bd55-45611a20b724"
            }
        }
    ]
}

This seems like a Graph bug? What does Http Call Notification Failure even mean in this context. The subcode 9999 also leaves a lot to be desired, I could not find a list of error codes anywhere.

The same request succeeds if replacesCallId is unset.

Reproduce the C# Graph SDK invitation request with replacesCallId set and compare its comms notification with the successful request where it is unset. Investigate the failed inviteParticipantsOperation resultInfo, especially the “Http Call Notification Failure” message and code 500/subcode 9999; done means the replacement call succeeds or the failure is clearly documented.