With input debugging enabled, it's easier to see that if the selection pin lands between the pre-close nail and the post-close nail then the selection collapses. In fact you can see this just editing <h1><a href='x'>foo</a> bar</h1>.

This is probably our selection resizing code triggering a selection collapse when dragging with pins.

On looking again, it seems enabling input debugging changes the behaviour (at least now it does).

Without input debugging, following the steps above results in the selection collapsing on touchend. With input debugging, the selection either is stable (if when touchend happens it lies entirely inside the text node "ไทย") or collapses immediately (as soon as the selection crosses the post-close nail).

Examining the touchend collapse with ve.Filibuster does not show any Javascript moving the selection, so it may be some obscure piece of code run via setTimeout.

@dchan it looks like you've done some initial investigations. What do you think the next steps are?

I am moving this to the freezer after talking more with David, it isn't a high priority.