I used /dh pregen start overworld 0 0 256 on my server. Took a few hours but managed to say it completed.
Upon logging in, I was able to turn on DH client side and see that LOD's were being generated around me, but they seemed to stop quite a bit shorter than a 256 chunk radius.
Exploring toward the unloaded chunks crashed my game when I got within my client chunk render distance (8 by default)
I turned on creative and flew up to see if it was my client taking a while to load the LOD's however after 12 hours I still saw the oddly short LOD radius, around 40 chunks instead of 256.