I've had multiple times that shift tab isn't working. 
This time, the game had to load for a long time, so after five minutes of staring at a spriggan, I decided to use shift-tab to spend my time looking at the steam thing.
I never had been able to actually click anything, but this time my cursor didn't appear at all. I started randomly clicking and moving my mouse and the spriggan in the background moved happily along. My cursor was still in the loading screen, but I was at the steam thing. After trying googling and trying everything I knew, I turned it off.
Not gonna do that again, but why can't I use the steam community?