Revisiting stairs climbed monitoring

I keep my Apple watch 3 updated, keep my iPhone bluetooth and cellular data activated when wearing watch and always have my phone on me during the day. My watch has previously recorded the number of flights of stairs taken each day but in the past week, the number has remained 0 both on watch and phone. I know that having both bluetooth and cellular on drains my battery faster. This morning I plugged in the phone (79% charged) while viewing the activity display and the stairs climbed went from 0 to 1 on both watch and phone. I had climbed the stairs twice so far this morning.

Any new insights or solutions welcome, otherwise I’m thinking its a case of planned obsolescence to make me want an updated apple watch. My watch was a gift which I’ve had for 2 years.

Thank you for any help