Ok, disclaimer, I have a 10K pull down resistor wired from the fan control pin GPIO 18 to ground. I did this so my fan will shut off when I shut down my Pi.
That being said, with the service loaded as normal, a short quick button press does nothing. Which is likely why I thought the button didn’t do anything. A longer press gets me a blue flash from the LED and likely a switch to manual mode. Pressing the button after that makes my fan spin for a second or so and stop. My pull down resistor may be messing things up on me though? Repeated short presses just get me the same short spin and stop. Holding the button down gets me another blue flash and it appears it goes back into auto mode. It’s turning on off at what I had set the service too.