Good evening. I am one of the new Monoceros user and encountered this unexpected modules outside my envelope boundary. Fortunately, I was able to get a quick response from Jan and his team. I hope these would also help other users if they encounter similar outputs from the solver. Here is Jan’s response:
The Modules are associated with geometry. That geometry is completely unrelated to the Module cage(s), so it can be also outside of the Module cage. You can think of the Module Part cages as of pivot for the associated geometry. The pivots are placed into the Slots and the geometry is placed along with it.
In your case I suspect that mistakenly one of your Modules is associated with geometry that doesn’t belong to it. When the Module is placed into the respective slot, the geometry is placed outside of your Slot envelope.
I suggest checking your Modules first - use the List item Grasshopper component and highlight your Modules one-by-one to find the broken Module.