Participants in peer-to-peer call empty

Describe the issue
I want to receive video streams from a user in a peer-to-peer call. In order to create a subscription i need access to the MediaStreams of the participant. I'm using a similar solution as in the AudioVideoPlaybackBot sample
The problem is that Call.Participants (ICall.Participants) is always empty and the event Call.Participants.OnUpdated not gets fired. If a third user joins the call or if the user sets the call to hold the event Call.Participants.OnUpdated gets fired and I also can access Call.Participants.

Is there a way to access the call participants in a peer-to-peer call?

Code Snippet
Subscribe to a video: code snippet from AudioVideoPlaybackBot sample

Expected behavior
Call.Participants not empty

Graph SDK (please complete the following information):

• Microsoft.Graph.Communications.Calls v1.2.0.4161
• Microsoft.Graph.Communications.Calls.Media v1.2.0.4161
• Microsoft.Graph.Communications.Calls.Client v1.2.0.4161
• Microsoft.Skype.Bots.Media v1.23.0.49-alpha

Start with Samples/V1.0Samples/LocalMediaSamples/AudioVideoPlaybackBot/FrontEnd/Bot/CallHandler.cs around line 198 and inspect how Call.Participants and OnUpdated are used. Reproduce the peer-to-peer call behavior with the listed SDK versions, then determine whether participant streams can be accessed; document the confirmed behavior or identify the required change.