I just tried to Quick Add a task with a Due Date of 9/30/2017 by typing Tab+Q, then Tab+D, then “9/30”. But as soon as I had typed “9/3”, the field immediately “auto-corrected” itself to “09/03/17”, with the insertion point (strangely?) in between the 0 and the 3. I had already typed “9/30”, so now I was looking at a Due Date of “09/003/17”.
I’m able to work around it, of course, but it’s clunky. So far I haven’t found a way to cleanly enter a date of 9/30/17 using the keyboard. If I don’t type a forward slash after the 9 (or “09”), the field’s value is cleared when it loses focus. But if I do type a slash, and then a 3, I immediately end up with 09/03/2017.
I prefer to use the keyboard whenever I can, but particularly when using Quick Add Task. Is this considered a bug? I only see this behavior when using Quick Add Task - the standard date picker doesn’t seem to have this problem, and entering “9/30” or “09/30” there works as expected. [Although I have to be sure to press Enter. When I press tab to leave the Due Date field, it’s left unchanged. Maybe that should be its own topic. 
]