I'm trying to get SEUS PTGI E12 to run with Enigmatica 6 0.2.7, without OptiForge it runs and shaders work, but model loaders are broken (I'd guess it's due to Optifine G2 not being compatible with Forge 32.0.108) and I get pink-black checkered cubes instead of many blocks. With
OptiForge I can see these blocks normally with shaders off, buth when I try to load shaders game crashes.

Here's crash report: https://pastebin.com/cReh1LCS

I can use shaders if I only install optifine, so I'm guessing it's actually optiforge problem.

Does the latest version of OptiFine and OptiForge fixed it?

Does the latest version of OptiFine and OptiForge fixed it?

For OptiFine, guess not. On Minecraft 1.16.4 Forge 35.1.37 OptiFine HD_U_G7, switching between shaderpacks doesn't cause issue on my obj block. In my test i tried switching between internal shader and SEUS V11. But when I turned off the shader, my obj blocks turned to purple and black blocks. Turning on the shader did the same.
Switching from internal to off causes:
[Render thread/WARN] [net.minecraft.client.renderer.model.ModelBakery/]: Unable to bake model: 'bcp:holey_fence_extension#east=true,north=false,south=false,waterlogged=false,west=false': java.lang.IllegalStateException: not enough data
Switching from off to internal causes:
[Render thread/WARN] [net.minecraft.client.renderer.model.ModelBakery/]: Unable to bake model: 'bcp:holey_fence_node#east=true,north=false,south=true,waterlogged=false,west=true': java.lang.ArrayIndexOutOfBoundsException: 6
I didn't install OptiForge, so I didn't test it