As far as I can tell, I’m having the same transition issue as mentioned above, and yes, your test case is in line with what’s going on.
I realize that it’s not theoretically a bug, but I have such extensive list/checklists (discontinuous) that all got mixed up with the new checklist behavior, and unfortunately the easiest way of dealing with it is checking the setting for “show checkbox in front of checklist parent.” It would just take too long to make and unmake all of the checklists in an order than keeps the boxes in the right places.
However, as the new behavior fails to meet my needs anyway, I don’t feel so bad about having to stick with the old one. I followed the discussion and was looking forward to the change, but it didn’t end up solving my issues with checklists in general. I appear to be in the minority that prefers more flexibility with toggling checklists (I would love to be able to toggle at will!) and likes to have bullet points nested under checklist items (like this guy). Still hoping for a way to make it work someday 