New Steam Controller can't control PC on Bluetooth until I first select Steam

Edit for the people who didn't understand: Steam is running. Steam Controller does literally nothing until I select Steam with my mouse. Then the controller works.

Original post: Windows 10, I have my puck attached to a different computer and until I can get a second controller this is the setup I get to use. This computer is attached to my TV. I don't use the Bluetooth on this computer for anything other than my Steam Controller, whereas the Bluetooth on my other computer with the puck is overloaded so I can't swap and use it the opposite way.

Does anyone know why the controller can't control anything on the computer when it's first turned on until I highlight Steam? Afterwards I can do anything I want on the PC. The controller connects just fine, it just will not work until I select Steam.