On July 23rd, Trusted Mode became the default mode for Counter-Strike: Global Offensive. Trusted mode in Counter-Strike: Global Offensive blocks third-party files from interacting with the game and as such, can have issues with NVIDIA gaming solutions (GeForce Exerience Share, NVIDIA Freestyle, etc.).
1. From the Steam Library, right-click over "Counter-Strike" Global Offensive" and select "Properties".
2. From the "General" tab, left-click over the "SET LAUNCH OPTIONS..." button. Next type the following line into the text field and click on the "OK" button:
3. Click on the "CLOSE" button.
4. Launch the game.
To allow 3rd party apps to interact with Counter-Strike: Global Offensive, you must disable Trusted Mode. To do this, follow the instructions below:
-allow_third_party_software
For more information on CS:GO Trusted Mode, please visit:
https://support.steampowered.com/kb_article.php?ref=8835-KLXV-0292