Conference call events different between Browser and Desktop calling modes

We have the Ringcentral embeddable integrated into our application. Some of our users use calling mode 'Browser' whereas others use 'Ringcentral for Desktop'.

In evaluating conference calling in our sandbox environment, I noticed that when in a conference call the rc-active-call-notify events are different between the two calling modes (Browser vs Desktop).

In the Browser case, when the conference call is active, we get an event that looks like this:

{
  "type": "rc-active-call-notify",
  "call": {
    "startTime": 1576070805908,
    "direction": "Outbound",
    "from": {
      "phoneNumber": "+1323..."
    },
    "toName": "Conference",
    "to": {
      "phoneNumber": "conference"
    },
    "telephonyStatus": "CallConnected",
    "sessionId": "0",
    "partyId": "p-a51...",
    "telephonySessionId": "s-a51c...",
    "offset": -1537
  }
}

Whereas in the Desktop case:

{
  "type": "rc-active-call-notify",
  "call": {
    "id": "ALr...",
    "action": "VoIP Call",
    "startTime": 1576070883606,
    "uri": "https://platform.devtest.ringcentral.com/restapi/v1.0/account/.../extension/.../call-log/ALr...?view=Simple",
    "direction": "Outbound",
    "from": {
      "phoneNumber": "+1323..."
    },
    "to": {
      "phoneNumber": "+1830..."
    },
    "telephonyStatus": "CallConnected",
    "sessionId": "882151...",
    "partyId": "p-20e...",
    "telephonySessionId": "s-20e...",
    "offset": -1418
  }
}

The Desktop case events are in line with what we were expecting. The Browser case event with
call.sessionId = '0' and call.to.phoneNumber = 'conference' is not expected.
Is there a technical reason why we do not get the same sessionId value from one of the initiating calls involved in the conference call (like in the Desktop case)?

The events in the Browser mode break our integration. Our integration is dependent on sessionId (and to some extent phoneNumber) values being related to the initiating sessionId values. A synthetic sessionId value of 0 break our relating the event to actual call sessionId.

Start by tracing the rc-active-call-notify event handling and comparing the Browser and Desktop conference-call payloads shown in the issue, focusing on sessionId and phoneNumber. Done means the Browser event behavior is made consistent with the expected initiating call identifiers or the discrepancy is explicitly documented.