No voice in one of the imported videos

Hi all.
I'm using AF version 23.1. Today my client sent me a couple of mp4 videos to use in a project. All videos are of good quality, play nicely in media player/VCL. Sadly after importing all videos to AF one of them is cimpletely silent in preview and after rendering. In the project window I can see the video has audio - it's properties are given and the soundwave symbol is showing below the video. The video is not muted in any way within the project which I checked multiple times following many tutorials and possibly all advice found around here. Setting up a new AF project, cleaning cache etc. did not help . Interestingly the same video has no problems with audio when imported to Premiere Pro, plays nicely with no errors or audible bugs. Do you have any advice on what might be the problem? 

Sadly I cannot share any of the files due to it being client work. 
I appreciate all the help and suggestions!