If you're on 9.0.0, just make a clean nand back up, download Atmo/Hekate, downgrade to 8.1.0 with Choi, create an emunand on the downgraded partition, then flash your original nand back.
I had 9.0.0 and this worked fine for me, albeit a bit of a tedious process and takes like 2-3 hours but it...