For a long time my family has used the HomePod intercom feature to intercom from the kitchen to our kids’ rooms on the second floor (“dinner’s ready!” etc). There are 3 HomePod minis on the second floor, each in their own room. The 3 rooms are all in a single zone called “Upstairs.”
In the last couple of months, this has stopped working. When I try “Siri, intercom to Upstairs,” it comes back with “I can’t find Upstairs.”
Any thoughts on what changed, or how I can regain this functionality?
As always, the first thing I’d try is to reboot all Homepods, iPads (I think that this was deprecated, but you may be on an older pre Matter version), and any Apple TVs which could be Home Hubs.
Looks like I found my (avatar) doppelgänger… 
How funny, I didn’t realize it pulled mine from Gravatar — I set that up years ago and completely forgot it existed until right now!
Thanks — all have been updated and rebooted, but are still unable to intercom to specific zones. I’ll keep digging!
Update for anyone searching this topic…this started working again recently! No updates on my side so not sure what changed but all is working for now.