Dialogue Manager Godot 4 Signals

Question

When using the Dialogue Manager addon on Godot, I am trying to run a function to change the sprite of a character. My function look like this under my character script:

func ace_change_sprite(index):
    print("EEE")
    change_sprite(index)

and my dialogue looks like this:

~ start
: test
Ace: Hey Miyu!
do emit("AceUpdateSprite",3)

When I run this, it prints the "EEE" but it doesn't update the Sprite. My character script is AutoLoaded and I have tried using signals, but still got the same result of "EEE" being printed but nothing else happening.

My change_sprite function is this:

func change_sprite(index):
    $Sprite.texture = load(sprites_path + character_name + str(index) + ".png")

It works when I call it within the player script, changing the sprite, but when I call it outside it doesn't seem to work.