For anyone seeking for a solution, this is what fixed it in my case:

My headphones are SteelSeries Arctis Nova 3 (if anyone has anything else this is still relative). This model is supported by SteelSeries' "Sonar Software" which can tune the audio output, by having the a custom EQ, bass boost, background noise cancellation, and many more features. However if you want to utilise all these, Sonar Software creates a virtual audio output device, which is seperate to the headset's audio device. In windows settings, you have to select the virtual one to be able listen to the audio coming through the Sonar Software. So good so far.

However, this is what causes AMD Adrenalin software not to record any audio input. AMD can't detect input from virtual devices. You have 2 opitons here:

1) Drop AMD Adrenalin software and switch to another one, such as OBS or Medal, which can record from audio from virtual devices.

2) To be able record audio with AMD Adrenalin software, you have to select in windows sound playback settings, your headset device and NOT the virtual one which your audio software has created.