Summary
In Unreal Engine 5.8.1, a packaged game freezes completely (unresponsive, must be force-killed) when a Niagara System using the Audio Spectrum Data Interface is activated at runtime. This is 100% reproducible - it happens on every single activation, not intermittently. The same Niagara system works correctly in PIE/editor on any version, and works correctly in a packaged build on Unreal Engine 5.7.4. The freeze only occurs in a packaged build on 5.8.1.
This appears related to the Movie Render Queue freeze reported separately here: UE 5.8 Movie Render Queue freezes before first frame when Niagara Audio Spectrum is active - same Data Interface, same final log line, same “worked in 5.7, broke in 5.8” pattern, but occurring during normal runtime gameplay rather than Movie Render Queue rendering, suggesting the underlying regression affects the Data Interface broadly rather than being specific to the MRQ pipeline.
Please select what you are reporting on:
Creative
What Type of Bug are you experiencing?
Audio
Steps to Reproduce
- Create a Niagara System using an emitter with the Audio Spectrum Data Interface, sampling submix spectrum data (e.g. via a “Get Spectrum Data” style module).
- Place the system in a level, or spawn it via Blueprint, with a way to trigger its activation on demand (e.g. bound to a key press).
- Test in PIE. Confirm it works correctly, no issues.
- Package the project for Windows using Unreal Engine 5.8.1, Shipping (or Development) configuration.
- Run the packaged build.
- Trigger activation of the Niagara system (e.g. press the bound key).
- Observe the application freeze immediately and permanently - no further log output, no crash dialog, process must be terminated via Task Manager.
- Repackage and test the identical project/system on Unreal Engine 5.7.4 - observe the system activates and works correctly with no freeze.
Expected Result
The Niagara System’s Audio Spectrum Data Interface should register its submix listener and begin sampling audio data without blocking the game thread, consistent with its behavior in Unreal Engine 5.7.4 and in PIE.
Observed Result
The application hangs indefinitely and must be force-terminated. No crash, exception, or error is logged. The last log line output before the freeze is:
LogAudioMixer: Display: Sending SubmixBufferListener ‘NiagaraAudioSamplingListener’ register command…
A process dump of the hung application shows the Game Thread in a “waiting on a lock” state, along with several other threads blocked on the same lock, and the audio device thread active inside FAudioMixerWasapiRunnable::Run. No exception information is present in the dump, consistent with a genuine deadlock rather than a crash.
Platform(s)
Windows (packaged Shipping/Development builds). Not reproduced in PIE/editor on any tested version. Not reproduced when packaging the same project on 5.7.4.
Additional Notes
This is a freeze/hang, not a crash - no Crash Reporter window or callstack is automatically generated, which is why a manual process dump was required to gather thread-state information. The affected Niagara system uses only the stock Audio Spectrum Data Interface (UNiagaraDataInterfaceAudioSpectrum), not a custom compiled Data Interface, suggesting the regression is in engine-level submix listener registration rather than in any third-party or project-specific code.