My NVR: TP-Link NVR1004H-4P hardware version 1.0
My Camera: TP-LINK C540V 1.0

When i record video's of my C540V webcamera, then from the mobile apps on tablet and samsung android phone, from the browser NVR ip, and from the VIGI windows app, i can play all my recordings in high quality and including recorded audio.So far no problems. When i export a piece of a recording in the Android app, i can do this for max 10 mins and the downloaded recording contains audio and high quality video. No problems!

However, when i export recordings from the windows app, it does not work properly.

I also learned when i lookup a specific day and time range in the Windows VIGI app, i can export it with a duration of 10 mins max. When i select the start and end time, keep it under 10 minutes and hit play first, i hear the audio, and all looks fine. Then i click the export button after which a Download Clips window pops up and the video is saved to my laptop. However, when i play the exported .mp4 video file, it does not contain any audio, only a quick 1 sec cracking sound and then no sound anymore. No matter which app i use to play the video, the audio is not there. Why?

Then the other approach i tried:
If i want to export recordings over a longer period of time, i have to login with a local admin account into the VIGI app on my Windows laptop, select my NVR device, go to Settings, Export Recordings and export the Continuous recordings or Event recordings. When i do so, i can find the files on my laptop, but when played i don't hear any audio. I have exported recordings in both the speed or compatibility mode, but it does not matter, the recordings have no audio.

Can somebody explain me what is going on here, or whether i am missing something ?