Games turns down master volume on the computer

[thomas.quiza]

After starting up the game for the first time, the game seems to turn down the master volume of my PC. The frequency is sporadic and the degree also changes between a very small amount, to a very rapid decrease, until the volume is zero and I have to turn it op again manually. It always decreases the volume, never increase. The decrease is not instant. It happens both in a training map and in the menu.

After restarting the game, the issue seems to have gone away. Managed to play a bot match without any issues.

 

[thomas.quiza]

The issue could be a red herring as I seem to experience the issue with the game closed. Of course minutes after I made the initial post.
However, I have never experienced this issue until immediately after launching the game.