Free camera - Q is not working

Hi, when I go to the free cam (TAB) everything works (WASD, E, ZX, PAGE UP/DOWN) except the Q key. It's annoying. It works elswhere (even if I want to type something in the search bar in TS4) and it shouldn't be bind to anything. Can you please help me with this? It's supper annoying when I cannot move down vertically in free cam. Thank you.