Holding my finger on the crown doesn’t start ecg on Apple Watch series 6

Apple Watch 6 running WatchOS 8.4.2

When instructed by the ECG app, I place my finger on, without depressing, the crown. There is no response. Any ideas as to why this might be happening? The watch shows no other faults, and the crown's push and roll manipulations seem to work fine. Maybe I'm dead? 😊