I had the problem that if I started CS GO in fullscreen it was always black. (Since april/may 2019)
I could hear the lobby background sounds etc, so the game was running but all was black.
A temporary solution was to make it in window mode instead of fullscreen, which worked somewhat, but not all the time. (-windowed in launch options)
BUT THE REAL SOLUTION (for me at least) was to delete ALL of my " launch options" in CS,
I dont know which one/ones that was causing this, but after I deleted all my launch options everything is now working perfect as before. And seems like many of my launch options was outdated anyway so seems like I am fine without them.
Just wanted to share this incase someone got the same problem.