In an outline view, grouped by priority, sorted by date, I was editing an item with a date that was right above an item without a date. I cleared the date and then started to edit the text of the item. In the middle of doing that, the item and the item immediately below appeared to switch places (based on the observed animation, presumably because a sort order change was applied since the date of the first item had been cleared), but after which both items had the same item text.
I actually have been able to recreate this but not 100% of the time, as I’m not sure of the exact sequence of actions. But it’s as if the sort swapped the items which then replaced the active item text editor control with the item text of the adjacent item and thus overwrote the original item text.