made a video showing the problem
https://youtu.be/zss6Ij8Gjgo

I'm having this issue also. Little Logistics 1.20.1.2 with the Big Moo Gaming modpack 1.0.22a.

It seems to me to be something to do with mobs because I've never had this issue where there aren't any before. Under what conditions can the links break?

Please provide more details. Which version is this? Modpack? Can you reproduce this in a fresh world?

Most likely this is a compat issue with another mod

I'm really wondering what mod you have that makes that when you pick up items, they go inside your inventory instead of your toolbar.