Since nobody tried to help with the issue, I found out for myself and I'm sharing it with you fellas.
If you use Bitdefender and it recently updated to 2018, check out the new Webcam Access permission, for some reason OBS Studio is blocked and you need to add it to the permitted list.
If you use Bitdefender and it recently updated to 2018, check out the new Webcam Access permission, for some reason OBS Studio is blocked and you need to add it to the permitted list.