cant split stacked items
No man is an island, but a bunch of dead bodies make a pretty good raft.
Make sure that you hold down alt button FIRST (before doing anything else) and keep it held down whilst you click and drag and drop, only then do you release the alt button.
If you do it right, you’ll see the box that prompts you for the amount to split.
The alt key is a button that often doesn’t get used much so you may not be aware of the fact that it’s not working. So I’d also suggest that you check that your alt button is in fact functioning. Maybe assign it as the weapon / attunement swap button, just to test.
(edited by Tarkaroshe.8370)