Object split (y) not working

I’m trying to split some faces into a new object, but once I have selected them, and pressed Y, nothing happens. The faces just remain a part of the object. I’ve tried using the menu (faces/split) as well to no avail.
I tried deleting the shape keys but that didn’t help.
I tried deleting the faces themselves, just to see if they were somehow locked, but they deleted just fine.
I know that’s not much to go on, but is there anything you know of that would prevent split from working?

Shortcut P separates selected faces into a new object
Shortcut Y just splits off the faces but does not make them into a new object

Ensure you are in edit mode and using the default shortcuts. File / Load Factory Settings to go back to defaults

aaaah, of course. Thanks so much, that was driving me nuts. P worked perfectly.