Summary
With Attenuate Voice enabled in Island Settings, proximity voice chat is silent: a remote speaker’s audio reaches the RTC room but is never rendered locally. Client logs show FortProximityChatBusPoolSubsystem failing to attach its submix (Set Submix on Voice Chat FAILED: Fortnite_Chat). The failure is intermittent (roughly 1 attach in 3 fails), and the subsystem re-initializes several times per session — when the last attach fails, the session has no working proximity audio.
Please select what you are reporting on:
Creative
What Type of Bug are you experiencing?
Island Settings
Steps to Reproduce
Version
Fortnite / UEFN v42.20 (Release-42.20, CL 58011042).
Island Settings used
- Voice Chat Scope: All
- Attenuate Voice: ON
- Full Volume Distance: 32 m, Falloff: +20 m
- Attenuation Shape: Sphere, Function: Linear
- Spatialize Voice: off, Focused Listening: off, Occlude: off
Repro steps
- In Island Settings → Voice Chat, enable Attenuate Voice with the settings above.
- Publish/push and start a session with two players on the Game channel (not Party).
- Speak while within Full Volume Distance.
Expected Result
The remote speaker is heard, attenuating with distance.
Observed Result
The remote speaker is not heard at all, even at point-blank range, whenever the session’s Sound Bus submix attach failed.
Platform(s)
PC
Additional Notes
Log evidence (client)
The remote participant IS transmitting and IS in the local room:
LogEOSSDK: LogEOSRTC: RTCParticipantsHistory NotifyParticipantUpdateAudioStatus.
AudioStatus=[AudioEnabled] ParticipantId=[[PUID]2f7...] <- remote speaker sending
Local player is on the Game channel:
LogVoiceChatManager: SetTargetActiveChannel ... NewTarget=GameServer
But the proximity Sound Bus fails to attach its submix:
LogFortProximityChatBusPoolSubsystem: [3c64] Initialized subsystem with a PoolSize of [5].
LogFortProximityChatBusPoolSubsystem: [3c88] Set Submix on Voice Chat succeeded: Fortnite_Chat.
LogFortProximityChatBusPoolSubsystem: [3c88] Set Submix on Voice Chat succeeded: Fortnite_Chat.
LogFortProximityChatBusPoolSubsystem: Warning: [3c86] Set Submix on Voice Chat FAILED: Fortnite_Chat. <- last init of the session fails
Across observed sessions the attach succeeded 4 times and failed 2 times — a race, not a deterministic failure. When Attenuate Voice is OFF (voice routed via EOSSDK instead of the bus) audio is heard normally, which points squarely at the bus render path (Fort.Rollback.RenderProximityChatAudioViaBus).
Impact
Proximity voice — the core of any RP/social island — is unusable with attenuation enabled. There is no creator-side workaround: the subsystem is native/server-side, not reachable from Verse, devices, or Island Settings, and the CVars are server-pushed. Creators can only disable attenuation (global voice, no proximity) or restart repeatedly hoping the race lands on success.
Suggested area
FortProximityChatBusPoolSubsystem submix attach ordering / race during session (re)initialization; the final init of the session is the one that renders client audio and is the one that fails.