ACL doesn't work at high world coordinates

[DriedShroomlight]

What needs to be done to get this working on 1.21.4? Rethinking Voxels had it working on 1.20.1 (r0.1_beta2). I'm unsure if it ever worked on Complimentary, but now both it and Rethinking Voxels have the same awful flickering and discoloration bug at high world coordinates. Surely this could be solved, right? Wouldn't mind helping out if you can provide any direction.

Edit: Better info.

[EminGT]

We believe it's a problem inside the code of Iris. Very likely the calculation of the "at_midblock" attribute losing precision at high world coordinates.