Lightmass Importance Volume height?

Hey friends,

Having a problem with Lightmass Importance Volume.

When I expand it horizontally, it also expands in the vertical. I am not scaling the volume, just setting dimensions and laying the volumes out next to each other. I can’t find anything online about this. Attached is a screenshot demonstrating the problem.

Using version 4.21.2 and have replicated it over two projects.