Unable to quickly swap items via keybinds

If I use a hotbar keybind to try to, say, place an item in my fifth hotbar slot, it rubber bands and does not let me. The same thing occurs when I try to use this to swap armour pieces quickly, either via hotbar keybinds or right clicking with the armour piece held.
Is this intentional? Is this a bug? It is a little inconvenient.

 

I'm not sure what causes it, but it's just how things work on Wynncraft the most part. You need to manually move stuff with your mouse.

It might be to prevent a major exploit (like a duplication glitch) or something, but I honestly don't know.

 

I’d wager it has to do with item locking