Pink objects and no fluid

[Uthon]

I'm using ObiFluid 6.0.1 and Unity 2021.1.4f1. When I load any of the demo scenes the geometry is all pink, and there is no water when I hit play.

Going to Edit > Render Pipeline > URP > Upgrade Project Materials seems to fix the pink issue with the geometry, but the fluid source remains pink and no water appears during play.

I get the same behaviour in HDRP.