At least we know that plugins or computation time aren’t an issue. Are you sure you internalised all referenced geometry? To test this, open a new Rhino document and then open your Grasshopper definition. Do you see more that the box?
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My guess is that the error happens on step 2. I don’t know what your process is to grab the four points of the box, but if you just take the first 4 points coming out of the “Deconstruct Box” component, the points you get will likely not be the same from one instance of Rhino to the next. This is a topic that is covered at length (along with the similar issues that come with the split and merge components in general) by Edwin in the webinar.