Add the mod lmft:
https://www.curseforge.com/minecraft/mc-mods/lmft
If there is no change, you have to remove the mods in groups/one by one until you find the one causing this issue
Remove these mods and combine OptiFine HD U I6 with Forge 47.2.18
Start with Optifine - without any other mods - if this works, add the mods one by one or in groups until you find the mod, conflicting with Optifine
Remove all mods and make a test just with Forge - if this works, add the mods one by one or in groups
Maybe you are using a mod which is not compatible with your current Forge build