This bug seems to affect items on the end of a task list. It doesn’t seem to affect very short lists. Lists of less than ten items seem to work. Once you have a list of ten or more, the save becomes random.
It’s easy to see in action. Edit a list of ten or more items in display mode and Save the note.
Here is an example of user input before saving on the left, and the data stored by the save on the right. Of course, any action that triggers a save, such as going into edit mode, or switching to a different note, will produce the change.