It's possible it may have to do with the version of Unity and Visual Scripting you're using. To be honest, I think I'm having a similar issue with it myself in the newest LTS version that I've been trying to troubleshoot. If it's the same problem, it is in relation to setting the parent on the placeholder that is created when you begin the drag.
I'm so frustrated xD I've been trying for over a week to get a simple drag/drop -> snap sytem implimented, I've watched maybe 5 tutorials (all with different methoids and results) and not one has actually worked xD Yours is the exact system I want to impliment, it seems perfect, specific yet flexible (and easily customisable!) but once again: I downloaded the assets, I follow the vid exactly and low and behold when i click and drag nothing happens, I can't get it to work xD I assume I'm missing something fundamental; I have a canvas with UI panels inside, the UI panels have the "over"-visualscript (with the downloaded asset nested inside it like you showed), I have a draggable object (simple sprite) with the variable component (and its contents like you showed) assigned, the "over"-visualscript (with the downloaded asset nested inside it like you showed) and if i hit run the sprite is immobile, can't be drag clicked or anything, no debug logs or errors. Edit: I even followed this instructions on the download page (regarding Canvas Groups, Layout elements etc) Do you have a discord or any way to back and forth if you dont mind? I'm at the point where if i can't even impliment the core mechanic to my game I may as well give up now and scrap the project lol.