Find my iPhone on HomePod not working

Hello,

I have updated my HomePod to iOS 12 and I am having trouble with the new Find my iPhone feature. The HomePod only seems to be able to find my main device and not any of the others in the house.

If I ask it ”hey siri, find my iPhone” it works every time, but if I ask “hey Siri find xxx’s ipad” or ”hey Siri find xxx’s iPhone“ (where xxx is either my name or my girlfriends name) then Siri replies with “I can’t tell if xxx’s iPad is nearby, you can check the location of all your devices at iCloud.com or in the Find my iPhone app”. Siri is correct and I can indeed see all these devices on the Find my iPhone app.

All the devices share share the same iCloud account and they are all updated to iOS 12.

Does anyone out there know if there is a setting somewhere which allows homepod Siri to find all the iOS devices linked to an account, and not just the main one?

Thanks.