I upgraded from iOS 11 to iOS 12.1. Before update Siri would listen after it speaks (e.g. - I say 'Hey Siri', then say nothing, then Siri prompts me with 'Uh huh', then I say something (without Hey Siri) - and it would still listen and respond accordingly).
After upgrade to iOS 12.1 Siri no longer listens after saying 'Uh huh' - so I need to start over with 'Hey Siri'.
Does anyone (or everyone) see the same behavior on their HomePod?