Working in MacOS.
After creating a new and relatively complex template (let's call it Template X), I decided to put it at the top of the list of templates - it's one I'll run most days, so it made sense to have it easily accessible. I tried to do this by dragging Template X to the top of the list - but instead of "landing" at the top of the list, it landed on top of the template which was already at the top of the list (call that Template A) - and the result was that I got a duplicate of Template A, and Template X vanished. No confirmation dialog like you get when you drag and drop tasks/subtasks onto other tasks. Nothing. Just...gone. Argh.
I've rebuilt my template now - and created a duplicate of it, just in case! But still...argh.
