Top and thin sides of slab will render invisible when placed vertically with shaders enabled through optifine

Thanks for the report, can you show me a screenshot please and for which mod, Minecraft and OptiFine version are you using?

The block is also completely see through from one of the large faces.

using Optifine 1.14.4 HD U F5 with compatibility through OptiForge (client will crash otherwise without it). Forge version forge-28.2.18. Doesn't matter what shader or resourcepack I use, this is always the result.

Complete modlist: --------------------------------------------------------------------------
☃ Snow! Real Magic! Snownee_ SnowRealMagic-1.14.4-1.5.2.jar

🥝 Kiwi Snownee_ Kiwi-1.14.4-2.6.3.jar

Advanced Chimneys EnderLanky AdChimneys-1.14.4-4.0.0.1-build.0072.jar

Carpet Stairs Mod EndlesNights carpetstairsmod-mc1.14.4_v1.4.4.jar

Collective Serilum collective-1.14.4-1.23.jar

Decorative Blocks stohun decorative_blocks_6b.jar

Double Doors Serilum doubledoors_1.14-2.1.jar

Double Slabs CJMinecraft01 DoubleSlabs-1.14-1.5.0.jar

Extended Lights polyvalord extlights-1.8.jar

ForgeEndertech EnderLanky ForgeEndertech-1.14.4-5.2.2.2-build.0084.jar

Just Enough Items (JEI) mezz jei-1.14.4-6.0.0.27.jar

Kottle Alex_wells Kottle-1.4.0.jar

Lotta Terracotta rahalabytes lottaterracotta-1.14.4-1.3.0.jar

MixinBootstrap LX_Gaming MixinBootstrap-1.0.3.jar

Nifty Squiggly_Androsa nifty-1.14.4-2.8.jar

OptiForge ZekerZhayard OptiForge-MC1.14.4-0.1.1.jar

Placeable Items Ferdz_ placeableitems-4.1.1.jar

Sit bl4ckscor3 sit-1.14.4-v1.3.jar

Snow Under Trees bl4ckscor3 snowundertrees-1.14.4-v1.1.1.jar

Sweet Concrete rahalabytes sweetconcrete-1.14.4-1.7.1.jar

Torch Slabs Mod EndlesNights torchslabmod-1.14.4_v1.5.jar

Upon further testing, the culprit is somewhere along that modlist, testing with only optiforge, optifine, and double slabs does not produce this issue. I'll look into this further.

Okay... it's not anything in that list. It's something to do with a mod I had installed and removed, but I can't for the life of me figure out what mod that would have been. Gonna keep digging, but I have no clue why this issue occurs and I can't seem to reproduce it through recreating the modpack as is. Gonna have to find what mod I installed and removed caused this issue.

Please try using the latest version of my mod as I included a specific fix for OptiFine in the update

Yeah, that fixed it. Wow you work fast. 👍

I fixed it yesterday 😂 glad that works. Let me know if you have any further issues!