[2020] I can't aim down sights in creative after the first round of any game.

Recently after the first round of zone wars or box fights i can no long ADS. I have figured that I can change my targeting keybind to something else but it wont work with the right mouse button. I have also discovered that if I swap my shoot and target buttons around its once again my right mouse button that doesn't work. My right mouse button still however works to change materials when building. My mouse is perfectly fine and it only is like this in fortnite and after the first round of any creative server.

If anyone could help that would be amazing.