`onBufferedAmountChange` is not firing

[zibet27]

Describe the bug onBufferedAmountChange never fires on macOS; other datachannel events work fine.

To Reproduce Provided example uses Kotlin:

val nativeChannel: RTCDataChannel = pc.createDataChannel(label, RTCDataChannelInit())
nativeChannel.registerObserver(object : RTCDataChannelObserver {
            override fun onBufferedAmountChange(previousAmount: Long) {   
                 println("onBufferedAmountChange: $previousAmount")
            }
}

val largeData: ByteBuffer = createBytes(100 * 1024)
dataChannel1.send(RTCDataChannelBuffer(data, true))

// Nothing happens; the time limit is 5 seconds.

Expected behavior The onBufferedAmountChange event should be fired once.

Desktop:

• OS: macOS
• Version: Sequoia