Mine don’t. And it actually upsets me that they won’t go away. If the day is over, and I don’t finish it, I would like to start the day with a clean slate, and not stare at what I didn’t accomplish the day before.

They dont disapper for me. The stay there for the next day if I did not tick them off

Could be they are scheduled for another day, they will appear on that day.

Is it just me or do uncompleted tasks disappear? 

Disappearing tasks?

This.  It defaults to being due today and when today ends the task just disappears.  I need things I brain dump to stay on the list.

No they were already in my list for that day and disappeared.