AK_SpeakerVolumeMatrix callback not applied immediately during playback?

Question

Using Wwise 2021.1.6.7774:
Specifying an AK_SpeakerVolumeMatrix callback for AK::SoundEngine::PostEvent:

Changes to the volume matrix within the callback no longer seem to be applied immediately, as they were in Wwise 2019.2.13.7577

Using the following code in the callback to force the volumes to 0 result in a first-pass click using wwise 2021, but works as expected (immediate silence) using Wwise 2019:

if (in_eType & AK_SpeakerVolumeMatrix)...

    AkSpeakerVolumeMatrixCallbackInfo* pVolumeCallbackInfo = static_cast<AkSpeakerVolumeMatrixCallbackInfo*>(io_pCallbackInfo);

    for (AkUInt32 uChannelIn = 0; uChannelIn < pVolumeCallbackInfo->inputConfig.uNumChannels; uChannelIn++)
    {
        AK::SpeakerVolumes::VectorPtr SpeakerVolumesForChannelIn = AK::SpeakerVolumes::Matrix::GetChannel(pVolumeCallbackInfo->pVolumes, uChannelIn, pVolumeCallbackInfo->outputConfig.uNumChannels);

        for (AkUInt32 uChannelOut = 0; uChannelOut < pVolumeCallbackInfo->outputConfig.uNumChannels; uChannelOut++)
        {
            SpeakerVolumesForChannelIn[uChannelOut] = 0.0f;
        }
    }

Comments

If you believe this is a bug, I suggest you submit a Bug Report (https://www.audiokinetic.com/library/edge/?source=InstallGuide&id=reporting_bugs).

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Note: the results above were from testing within the context of the latest Unreal integrations, corresponding to the Wwise versions mentioned.

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Bug report submitted.

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I'm happy to report this has been fixed in Wwise 2021.1.10:
WG-59298 Fixed: Changes to the volume matrix in the AK_SpeakerVolumeMatrix callback only take effect on the next audio frame.