Is there a way to make MixMonitor record transmit audio feed with silence?

I need to record call into stereo file, where one channel is receive feed and second one is transmit feed.
MixMonitor provides an ability to do this by using its r and t options but here is a problem:
it’s something like voicemail app and it plays specific audio files to caller using Playback() and the crucial part is that MixMonitor isn’t able to record transmit silence.
Look at the screenshot

MixMonitor only records transmit feed when I play something (ie. it only records playback in sequential order).
But it causes desync between receive and transmit channels and now there is no way to merge them manually into stereo file (as I want) because they have different length.

So the question is what can I do now?
Documentation says that MixMonitor runs as audiohook so that’s probably why it doesn’t record silence because there is no input at all when my voicemail app doesn’t play file.

I guess I can use Monitor (it records everything as needed) but it seems like Monitor runs in the same thread and I’m worried about potential performance issues.

Any help is appreciated, sorry if I explained bad, English isn’t my native language :sweat_smile: