I had this problem since I bought my Huawei Mate20 pro. When i record my voice either by using the Voice Recorder app or by making voice messages in any application such as WhatsApp or even the vedio recording, I almost have no sound. You can hear the first milliseconds of my voice and the rest is silent.
I went to App permission/ Microphone and kept only the phone main apps to use the microphone such as Phone and Voice Recorder, but still the same problem.
The voice recording problem disappeared only when I restart my phone until I use the private space it comes back again.
I noticed many people complained about this issue in here but no solutions for it.
Did you came up with a solution?