iPhone 8+ video sound issues on import - HEIF / HEVC videos

I am having sound issues when importing videos recording from various iPhone 8Plus to Adobe Rush desktop macOS. 

The video files sounds like there is a an distortion filter added. 

Even if I deactive every additional automatic audio correction within Adobe Rush (like discussed in other articles), the files remain unusable. If I reduce the gain to 25% the file sounds somehow ok - maybe because it is so quiete that I hardly hear anything or can not make any judgment about the sound quality. 

macOS 10.15.6

iOS version 13.6

Recorded app: Native camera app from Apple
Fileformat: HEIF/HEVC

8bit HD (1-1-1)

1080p (30fps) 

Audio settings readout from Quicktime:
mono, AAC, 44100 Hz

Quickfix:

1. If I use Adobe Premiere - there is no issue at all and the sound seems great.
2. If I start the project on my phone in the mobile Rush version, import the same file, save & sync to Adobe Cloud, I can open later it on my Mac and the sound issues are gone. 
   
   
   Tested with two iPhone 8+ over a period of time from Oktober 2019 until August 2020 (latest tested with Adobe Rush 1.5.20)
   
   Would be nice to get a fix somehow, because Rush is a great pice of software and totally future orientated. 
   I've added one example video. 

Steffen