What are you expecting it to do? Excuse my ignorance - I don’t have an Ace but I can’t think of a reason to need an LED. 

Hi ​@Waxounet 

Welcome back to the Sonos Community!

I just checked this with my own Ace for a short time and saw no LED activity whether Head Tracking was activated or not. Could you please describe what you see with and without Head Tracking activated? Thanks.