Here is a "full" explanation on invalid slots with arrows, you can skip the part about theory if you want
First you will need to transfer a lot of arrows slots, the goal is to make a bow tab have more than 20 slots. We need enough arrows to fill up from the bow slots you have to the 20th slot. For example if you have a default bow tab, you will need 15 arrows slots. Over that we need arrows slot that will be in unreal slots. The minimum is 1, but depending on the setup you might want more.
To transfer arrow slot follow this setup for example with a fully progressed save :
- make a new save
- get sheika slate and 1 normal arrow
- get a save1
- break 7+ slot on the progressed save
- load the same number of times the save1
- load progressed save
Then you have enough arrows slots

A bit of theory, we have 2 cursors the real one and the temporary one (don't why the real one is for tbh), when you move into another tab you can move the temporary one before the real one sync up. If you move into a unreal slot, only the temporary cursor can go into them and the real one can't so it creates an invalid slot (why not?)
To get an invalid slots you need to :
- go to a tab next a arrow tab on last row
- move into a arrow tab
- quick tap D-pad down
-> your temporary cursor is on a unreal slot
If you perform multiples quick tap down (or just hold) you can reach another row of unreal slot, you have as many as you have transferred arrows slots.
Now when it sync up, we need to know about 3 tab theory, consider that when we cross the last row on the n tab slot, we get into the n+1 tab slot. But if you get past the 3rd tab, you get into the star icon and after into the system tab.
So basically if you don't get what you're aiming for, you might have a wrong tab alignment and so you need to change it by doing for example : be on a other tab than sword, throw a sword and pick up
If you have an invalid slot in a items tab or in system tab, you can chain it to get a invalid slot in any items tab but it requires a few techniques
If you want to go easy, you can just directly get the invalid slot where you want like this (let's note it raw r and col c) :
- go on a tab next to an arrow tab which is in tab slot 1 or 2
- go into raw 4, col c
- joystick into the arrow tab
- quick tap dpad down r times
- wait for sync

What can we do with a invalid slot now and in what slot do we need it? A useful use is to desync a prompt from pressing A on a item (source) onto another item (target)
Following this you will get a invalid slot on the tab to the right from arrow, we need the target item and source item to be on the same tab slot (mod 3), raw and col.
After getting the invalid slot, we quick tap joystick right into a tab next to the source item (your cursor should be on it), we move to the system tab, wait for resync and move back to item inventory
-> since we are consider to move into this slot, we have stored what happens if we press A
Then same thing, quick tab joystick right into a tab next to the target item (our cursor should be on it) and press A
Note that if you want to hold a lot of things, the drop prompt is preferable to the hold prompt