@Mark Reategui (pentagramwookie) I have the same system: MBP 16" with Radeon pro 5500m, and using Bill's (@Bill Wurtz (billwurtz)) solution above worked from me.
If you use Node Wrangler, then just replace the Texture Coordinate node with a Geometry node. I have:
Geometry (position → vector) Mapping (Vector → vector) Gradient texture (color → fat) Color Ramp (color → density) Principled Volume (volume → volume) Material Output