Acoustic Echo Cancellation does not work initially

I have a voice app that is both playing and recording audio. I have enabled voice processing and am setting AVAudioSession.Category to .playAndRecord and AVAudioSession.Mode to .voiceChat.

When the experience first launches, we play a greeting. The first few hundred milliseconds of that greeting are being captured by the inputNode before AEC seems to start working. Is there any way to get AEC working the entire time? For now we've had to disable recording while we're playing audio, but would prefer to both play and record simultaneously.

Here's some code snippets:

public init(denoiseModelPath: URL? = nil) {
    noiseReducer = denoiseModelPath.flatMap { NoiseReducer(modelPath: $0) }
    recorderNode = engine.inputNode
    speakerNode = engine.outputNode
    mainMixerNode = engine.mainMixerNode

    engine.attach(audioPlayer)
    engine.connect(
        audioPlayer,
        to: mainMixerNode,
        format: nil
    )

    playbackFormat = mainMixerNode.outputFormat(forBus: 0)
}

public func setupAudioSession() async throws(AudioError) {
    do {
        let audioSession = AVAudioSession.sharedInstance()
        try audioSession.setCategory(
            .playAndRecord,
            mode: .voiceChat,
            policy: .default,
            options: [
                .defaultToSpeaker,
                .allowBluetoothHFP,
            ]
        )
        try audioSession.setActive(true)
    } catch {
        throw .audioSessionSetupFailed(error)
    }

    do {
        try recorderNode.setVoiceProcessingEnabled(true)
        try speakerNode.setVoiceProcessingEnabled(true)
    } catch {
        throw .enableVoiceProcessingFailed(error)
    }
}