There are a few differences between the sample and my code.
First, the biggest, is in the sample the drop is where ever your cursor is and you let go of the mouse. On mine, when dropped, it is in center of the entire diagram.
Second, my code is set up in Vue, specifically using NuxtJS, following this example where there is are two components : Minimal GoJS Sample in Vue.js
I just tried using just the exact code from the Drag and Drop example. I tried it where everything was in the Mounted() method and it worked just fine. I am guessing I am somehow not passing the location correctly between the two components? Which I find odd since I am able to pass different names of the nodes, color, and etc. Is there something special for location points?