I just realized that PlayerController might be causing the issue, because clients only have their own PlayerController, but not the other PlayerControllers in the game, so it can’t multicast because clients don’t have any PlayerControllers on their machine except their own.
You will have to do this logic on your Pawn class instead.
I googled “ue4 multicast playercontroller” and found a bunch of stuff, if you’re interested, you should read through some of it.
https://answers.unrealengine.com/questions/818293/calling-multicast-function-from-playercontroller-p.html