Iron Golems Stepping Particles on Custom Fluids Has Null Texture

I added Overwarm Lava on my own mod. I was making fun of pulling iron golem into a pit of Overwarm Lava.

Steps to Reproduce:

1. Create a 2x1x2 pit of custom fluid.
2. Summon an Iron Golem.
3. Pull him below the pit.

Observed Results:

The stepping particles you may notice are weird, but called Null.

Expected Results:

When the Golem steps on the lava or water, it shows step particles of lava/water. With the custom fluid, should be the same.