Watch does NOT lock anymore

The “lock” feature on my Watch has recently changed. What used to happen was that the watch would lock each time that I took it off my wrist and put it on my charging stand. And every time that I would take the Watch up and put it on my wrist again, I would need to “unlock” it with my iPhone.

Recently, this changed. The Watch no longer locks at all. When I lift the Watch to put it on, it is already unlocked. Naturally, this triggers one of the apps on the Watch face, as one of my fingers is likely to tap the icon during the putting on of the Watch.

This has become annoying. I’d like to ensure that the Watch is locked whenever I take it off. I looked for a fix online (including some places in these Apple forums). They tell me to go to Settings (on the Watch), Passcode, and turn “Wrist Detection” to OFF. When I do this, the Watch gives me the message, “If you turn off wrist detection: your Apple Watch will not lock automatically, Heart rate tracking and notifications will be turned off”, and some other details.

I need to be able to monitor my heart rate. That is the one reason that I got the Apple Watch.

So, what changed? And how do I fix this? I don’t want my Watch to be unlocked when I’m not wearing it.

Watch model A1978

Apple s/w version 8.7