@bvado Sorry that I didn't answer this, but I didn't get a notification about a new post :-(
COL Reminder's notification were always sticky/not clearable, but some users reported that they can now be cleared.
After investigation, I have seen that on Android 13 and up, Google has changed this, and I need to add "ongoing" to the notifications to get this working again.
Before Android 13 it was enough to send it only as "NO CLEAR":
Bit to be bitwise-ored into the flags field that should be set if the notification should not be canceled when the user clicks the Clear all button.
With Android 13 I need also the flag "ONGOING" to achieve this because the "NO CLEAR" does only prevent to clear it if you tap on "Clear all", but the user can swipe it manually away.
I don't know why Google has changed this.
And some smartwatches don't show "ongoing" notifications and this is why you don't get the notification on your watch.
But I am checking if I can add this change only for Android 13 and up.
So it would work again until you have a phone with Android 13.