Why are my hotkeys not working in Minecraft?

So if I connect my 1st and 2nd slot with the 2 hotkeys on my mouse, I can't move items from a box directly to the 1st or 2nd slot by pressing the mouse button, as it normally works. I play with labymod. It works strangely with Lunar and BadLion. Does anyone know why this is?

Doesn't work for me either, use Labymod

So you assigned the first two slots with the mouse buttons, right? Are you already occupied with dismantling and building? If so, it's because. If not, then bye

Nope, I have side buttons that are not yet assigned.

Oh… I don't know how to help you.

I have assigned my two side button on my mouse to slot 1 and 4 but when i clickthe button to go to slot 4 it goes to slot 1 and i have no idea why