If you go into edit mode on a card and cut a parent, then pressing cmd + enter doesn’t finish editing like it normally would and, I think, should.
Thanks for the bug report, good spot! This is happening when you close the “Manage parent” menu, as it doesn’t auto-focus your cursor back to editing the card content. The hotkeys to cancel and finish a card don’t work unless you are actively editing a card.
We will make sure to fix this in the next minor update, so when you close the “Manage parent” menu it will automatically focus your cursor back into the card where it was last. So you can continue editing, cancel or finish a card with your keyboard.