Helllo CrucifiedRonald, thanks for posting and welcome to the forums.
There are several fixes for mic and audio issues we can go through, but first I would like you to have a look at the following 5 steps -
1. First of all can you try lowering the games 'Voice Chat Record Threshold' in the games audio settings to zero, this should allow the mic to be picked up with the slightest sound.
2. Next try changing the audio settings in game from push to talk to open and experiment with the two.
3. Could you next try changing the display options in game to run in borderless window and then full screen mode and see if this makes a difference.
4. Next, can you please make sure you have the correct device set up in Windows and in the games settings to pick up sound - some motherboards use separate audio channels for a device depending on if you have your headphones/mic plugged into the front of your PC or back of your PC.
5. Finally, please follow every troubleshooting step in our support article here to make sure you have not missed any steps -
Please note that depending on what country or what server you are connected to, this can also restrict you voice chat use in game, please see the article above for more information.
Please let me know how you get on after trying the above steps and we can try looking at a few more things that may help you?