Ok so I’ve got an Apple Watch series 5. Only had it since Oct 2019, I actually wasn’t sure when it stopped but like you haptic was not tapping my wrist for messages notifications. Haptic taps we’re working for everything else, fb messenger, calendar, like literally every other notification was haptic tapping.
I went through everything I could think of. All the settings. Resets. Ensured up to date OS. I tried all of it. Then talked to Apple. Ended up having a new watch sent and I sent back the old one. New watch still exact same problem.
talked to Apple again, the support person told me a setting I hadn’t tried yet, on the phone for the phones messages settings-messages-send and receive set “start new conversations from”, made that my Apple ID not my phone number... was all excited, still didn’t fix it.
so drum roll please, I went to bed, got up the next morning, figured I would just continue changing things, finally found it. And from my experience, what worked for me may not work for you, but it doesn’t hurt to try:
the way I had haptic set up for my phone I didn’t have any vibration set on my phone. BUT not only that, there’s also a second part to that, you can make custom vibrations for the phone, and in that menu I had it set to “none”
so when I changed that it some how undid the issue.
so on the phone: Settings-Notifications-Messages-Sounds-Vibrations- and in there I just created a custom vibration.
right away after changing that I had the watch set to mirror the phone for messages notifications, IT WORKED, then after I changed things back, back to the way it was before even when it didn’t work, and it worked. lol 😂
I wish you luck and hopefully this works for you.