No audio in screen recordings on Android 10

I have several phones, all of them on various versions of Android 10 and 11. I am using an app to make conference calls and I need to record those conference calls. My main device is Huawei P20, but the same problem occurs on all the Android phones I have. When I try to screen record the calls, there is no audio at all. I have tried a bunch of screen recording apps, including the one that came with the system and all the major screen recording apps available. Same problem. I have also checked and tweaked the sound settings and did everything I could, (internal, mic, mic + internal/system have all been tried) but the problem persists. A lot of screen recording apps say if the Android version is lower than 9, there might be issues with the audio, but 10 and above shouldn't have any issues. One error message comes up sometimes: app ABC (that app's name) is recording audio (or using the mic) so the audio can't be recorded. I don't know what that means, because all I need the screen recorder to do is to faithfully grab the audio from the system. I tried screen recording the same app on iPhones and there was no problem at all. The audio was clearly kept.