I have Razer Ornata Chroma and I'm using Razer Synapse to customize RGB on the keyboard. I noticed that I'm not able to use Shift+Ctrl+A keyboard in one of the apps I'm using. When I exit the Synapse application, I'm able to use the shortcut successfully.
For me, the problem was Razer Cortex. Under FPS, there's an option for a keyboard shortcut to show/hide the FPS display and the keybind default is ALT + SHIFT + Q. Just changed it to some random keybind and everything is fine again.