Forge Version: 40.1.68
Quark Version: Quark-3.2-358.jar
AutoRegLib Version: AutoRegLib-1.7-53.jar
Rubidium Version: rubidium-0.5.3a.jar

When Corundum blocks are placed behind Stained Glass blocks, the face of the corundum blocks don't render from some orientations. The issue occurs with both Vanilla Stained Glass, and Quark Stained Framed Glass, but not regular Glass or regular Framed Glass

This is what the expected behavior is with just Forge, Quark, and AutoRegLib

This is the bug when Rubidium is installed as well

Related to Translucency Sorting, waiting for 0.5.0 Sodium with fix.

I also tested with Forge Version 40.1.80 (the latest release available in the Curse Client at the time of writing) and the bug still exists.