Homepod will not play VoiceMemos!

I record hours of my music performances every week from the stage via VoiceMemos on my iPhone15 Pro to listen back to. When I elect "my room" which plays through dual (original) HomePods seamlessly for my Apple music and podcasts it retains the "my room" setting for a few minutes than defaults back to iPhone as the speaker choice. I can close all apps and restart the phone after which i might get an extra minute of iPhone-HomePod success but a soon enough it defaults back to my iPhone. Mega-Thx for any attempted solutions!