No matter what I do, custom sky textures in resourcepacks will not work. I have tried multiple different packs, and while everything else works fine, the sky stays default. I have custom sky ON and a render distance of 25. I run shaders, and the sky stays default for Sildur's enhanced default, Sildur's vibrant extreme VL, and Continuum 2.0, as well as without any shaders enabled. I've messed with settings in Sildur's VExVL enabling the default/custom skybox setting, etc. No use. I run Minecraft using MultiMC and not the regular Minecraft launcher so MCPatcher isn't really an option for me. I am using Optifine HD Ultra E3. As far as I know, no other mods I run edit the sky, except for maybe BoP when it changes the sky colors for certain biomes.
Thanks to anyone with advice/help. xoxo