ReplayKit using WebRTC stops working after going to background repeatedly

Question

I'm using WebRTC to create a peer to peer connection for sharing screen and audio. I'm capturing the screen using ReplayKit, which generates CMSampleBufferRef; using that I can create RTCVideoFrame.

To get the CMSampleBufferRef I'm using:

[[RPScreenRecorder sharedRecorder] startCaptureWithHandler:^(CMSampleBufferRef  _Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error)

Up until this point, everything works perfectly.

The problem arises when I start sending the app to background and come back several times; then ReplayKit stops calling his capture handler. This only happens if I send the CMSampleBufferRef to WebRTC, so it's clear that the ReplayKit issue is related to WebRTC. If I delete this line from the code, the issue doesn't happen (clearly WebRTC wouldn't work, though).

[self->source capturer:self->capturer didCaptureVideoFrame:videoFrame];

The only way I can get it to work again is to restart the device. Even killing the app and restarting doesn't work.

This is how I create RTCVideoTrack in my view controller:

- (RTCVideoTrack *)createLocalVideoTrack {

   self->source = [_factory videoSource];

   self->capturer = [[RTCVideoCapturer alloc] initWithDelegate:self->source];

   [self->source adaptOutputFormatToWidth:441 height:736 fps:15];

   return [_factory videoTrackWithSource:self->source trackId:@"ARDAMSv0"];
}

Here is how I convert the CMSampleBufferRef to RTCVideoFrame and send to WebRTC:

- (void)didCaptureSampleBuffer:(CMSampleBufferRef)sampleBuffer {

  if (CMSampleBufferGetNumSamples(sampleBuffer) != 1 || !CMSampleBufferIsValid(sampleBuffer) ||
    !CMSampleBufferDataIsReady(sampleBuffer)) {
    return;
  }

  CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
  if (pixelBuffer == nil) {
    return;
  }

  RTCCVPixelBuffer *rtcPixelBuffer = [[RTCCVPixelBuffer alloc] initWithPixelBuffer:pixelBuffer];
  int64_t timeStampNs =
  CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer)) * NSEC_PER_SEC;
  RTCVideoFrame *videoFrame = [[RTCVideoFrame alloc] initWithBuffer:rtcPixelBuffer rotation:RTCVideoRotation_0 timeStampNs:timeStampNs];

  [self->source capturer:self->capturer didCaptureVideoFrame:videoFrame];
}