Hi Frequia,
I’m glad you’ve got it working. I’m not sure if this is a direct limitation of Lightmass Importance Volume. It is best to keep these down to areas that are more where the player will be able to access. Having one covering an area as large as that is probably not the best solution.
If you run into any problems with your new build having a similar issue feel free to post your questions here.
Thank you!
Tim