On PC after the initial hidden blade training with the Assassins ledge kills don't work. When under an enemy standing by a ledge you get the prompt to ledge kill but tap the key and nothing happens. Whistling causes them to detect you or they jump off the ledge searching but you still can't ledge kill them.
On PC for keyboards please make raiding a separate button to primary interaction. I prefer to have primary interaction and mount/dismount mapped to the same key (it's just easier that way). Every time I push to raid Eivor dismounts instead, even of tapping.