Give us a toggle to show/hide other players during challenges

Title.

Let use choose whether to see other players during challenges.

Other players disappear when working on a challenge and no toggle for this is a problem. This means for a large chunk of play time, you won't see other players as either you or they are invisible.

I understand that certain environments can change when a challenge is loaded, and that players might want everything to disappear during a challenge to they can focus on the line, but this has to be an oversight. 

Give us a toggleable option to see other players when running challenges. Make them "ghost" players, 50% transparent, if needed.