For the X570 Taichi go to
Advanced>AMD CBS>NBIO Common Options
Make sure you have “IOMMU” set to “Enable” (Auto doesn’t work).
Also make sure “Enable AER Cap.” is set to “Enable”
Once you’ve set that an option called “ACS Enable” will show up, I left that set to “Auto”.
After that’s done you’ll have the normal X570 IOMMU groupings.