reminders not syncing between Apple Watch and iPhone (or iPad or Macbook)

Well, as I said, I had even gone as far as to “Reset” my Apple Watch using the “Erase Apple Watch Content and Settings” option, once selecting the “use a backup” option and once using “set up as new” option when adding it back to my iPhone 11. This did NOT fix the problem. But, yesterday I purchased a Series 6 watch to replace my Series 5 watch. I first erased the the Series 5 watch using the aforementioned Reset option, then completely removed it from my account via iCloud.com. Then I set up the Series 6 watch as a new watch (not using a backup). This FIXED the problem. So, clearly the problem was with my Series 5 watch. Not sure what could have happened to it, but something clearly happened when it upgraded the iOS to 7 recently that just could not be fixed by anything I could do.

Hi. Thanks for the response. I do use Reminders across all of my Apple products (Apple Watch series 5, iPhone 11, iPad Gen 6, and a new MacBook 16”. I checked and tested Reminders behavior across and between all of these devices and they all seem to work fine EXCEPT for the Apple Watch series 5 which used to work prior to the WatchOS7 update (it is currently running WatchOS 7.0.2). With the exception of the watch, my Reminders are updated almost instantly between all of my devices. However, my watch does not sync with my other devices at all. No new reminders created elsewhere are showing up on my watch and no reminders created on my watch are showing up anywhere else. The same behavior occurs with reminders marked as completed or that are edited. No changes are syncing to or from the watch. Something is definitely broken here and I am at my wits end to fix it.

Hi. I've read the page you referenced above, but I don't think it applies to my problem. I update all of my devices immediately when new updates are released. My devices were updated to iOS 13 in September of 2019 and they are all running the latest software now (iPhone is 14.1, iPad is 14.1, Macbook is Catalina 10.15.7, and Watch is 7.0.2). I have opened Reminders on all of these devices and none of them are indicating that they need to be updated. And, I even uninstalled and reinstalled Reminders on both my iPhone and my iPad, but still don't get any indication that I need to do anything to update Reminders as detailed in the page you referenced. I even went as far as to log on to iCloud.com and pulled up Reminders there, but again saw nothing indicating that there is a problem regarding a needed update.

And, I also Erased Apple Watch Content and Settings and re-synced it with my iPhone today as a New Device, not from backup (which is what I had done previously). Still the problem remains.

My watch is not syncing Reminders back to my iPhone, iPad, Macbook, or iCloud.com.

I should add that the problem I am having only began coincident with the recent WatchOS7 update. I've owned the watch for a year and it has always synced properly until now.