I've made a simple mod and my textures, models, and blockstates are recognized and show up in the game, but my localized names simply do not.  The mod is called Yo-yo so I have the ./src/main/resources/assets/yoyo/ folder, which contains blockstates/, lang/, models/, and textures/.  I set the item's unlocalized name with setUnlocalizedName("yoyo_placer").  Minecraft correctly picks up the model and texture and getUnlocalizedName() returns "item.yoyo_placer", but the name still shows up as "item.yoyo_placer.name" in game.  My language is set to en_US, my language file is in lang/ and named en_US.lang, it is a UTF-8 text file with a BOM and LF line endings.  It is in the same location and format as every tutorial I can find.  Most big name mods on github seem to have the resources folder somewhere else but the structure within it is the same.  The code can be found here: https://github.com/hacatu/yoyo.  I am running Minecraft 1.11, Minecraft Forge 1.11-13.19.1.2199, Forge Gradle 2.2, Gradle 3.3, Groovy 2.4.7, Ant 1.9.6, Java 1.8.0_112, and Arch Linux 4.8.13-1 64 bit.

I suspect the issue is with your pack.mcmeta file specifying

pack_format

as 1.

 

1.11 requires all resource file names to be lowercase, but if a resource pack specifies

pack_format

as 2 then lang files will still be loaded with mixed-case names (e.g. en_US.lang). If a mod doesn't include a pack.mcmeta file, Forge will provide a default one that specifies

pack_format

as 2 (allowing mixed-case lang file names).

 

Because your

pack_format

is 1, this doesn't apply and your resource pack is treated as

pack_format

3 (requiring all file names to be lowercase).

 

Either change

pack_format

to 2 and leave the lang files as-is (e.g. en_US.lang) or change

pack_format

to 3 and convert their names to lowercase (e.g. en_us.lang).

Thank you, changing pack_format to 2 does fix it.  Removing pack.mcmeta altogether also fixes it, I guess because it defaults to good values.