GameObject.Find returning null on player prefab Mirror multiplayer

When my player and the UI which is a child of the player spawn, one UI element uses GameObject.Find in Start to get a reference to another UI element. For some reason it is returning null, even though UI#2 is not deactivated and the exact same code works in the single player version of the game. I would guess it is something to do with the order scripts are executed and objects are spawned but I have read the docs and can’t find any explanation.