This is new. When opening a project that has moved or missing elements, the selection dialog doesn’t display a prompt so you have no idea what it might be looking for.
Feedback forthcoming…
Already reported
Thanks Apple
That image doesn’t show FWIW
Yeah, I realized I had to edit it. Fixed now.
Thanks for letting me know it’s been reported.
Use the prompttext property. That is shown on El Capitan.
(I know it doesn’t help on the missing file window but at least you can handle your own dialogues)
I love drop box … no image yet again 
Oh excellent! I attached it to the Feedback case you posted.
Not as good as having a window title on top of the file dialog or brewing one’s own, but displaying a notification right before the file selector can work.
This is an OS X level change
Thank Apple