Widget won't show on client if bound to a function

I’m trying to show a countdown timer on the player’s HUD in a multiplayer game. It works fine on the server/local, but it won’t show up on the client. I can get a plain text widget to show up on the client’s HUD, but when I change the widget content to be bound to the function (to get the countdown timer) it doesn’t show up.

Where am I going wrong?

Updated screenshots, still no idea what I’m doing wrong.