Change AudioUnit from VPIO to RemoteIO occurs the volume was reduced (iOS 14 only)

When I change audio unit from VPIO(VoiceProcessingIO) to remoteIO, the volume was reduced and can not restore to normal level.

There's a workaround by this post:

h ttps://trac.pjsip.org/repos/ticket/1697

I use the workaround in my code and according flowing steps:

1. stop and destory all the running IO AudioUnit (remoteIO and VPIO)

2. run workaround code

Code Block 
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryRecord error:nil];
[[AVAudioSession sharedInstance] setActive:NO error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord error:nil];

3. setup remoteIO and run.

and it work perfectly! The volume of remoteIO was go to normally.

But sadness happens on iOS 14, the workaround is not work at all.