Description of the issue:

The OptiFine option "Render Regions" causes multiblock structures such as the Coke Oven to be invisible and cause other nearby blocks to turn invisible. Turning off Render Regions under the Performance tab fixes the issue (I don't expect this to be fixed since OptiFine is not officially supported, I'm just making this so that people who are having the same issue will be able top find the solution).

Versions & Modlist

ImmersiveEngineering - 1.16.1-3.1-112
Forge - 1.16.1-32.0.108
OptiFine - 1.16.1_HD_U_G2