[1.12] Mod works in dev environment but not after being built

Hey guys,

I recently added Mixin to my mod and it all works fine in my dev environment. However, after i ./gradlew build it, the jar isn't picked up as a forge mod.

From the looks of the logs, the core mod (mixin) is loaded but the mod itself is never loaded somehow. Please help!

here's my gradle:

buildscript {
    repositories {
        jcenter()
        maven { url = "http://files.minecraftforge.net/maven" }
	    maven { url "https://plugins.gradle.org/m2/" }
        maven {
            name = 'sponge'
            url = 'https://repo.spongepowered.org/maven'
        }	
    }
    dependencies {
        classpath 'net.minecraftforge.gradle:ForgeGradle:2.3-SNAPSHOT'
	    classpath 'com.wynprice.cursemaven:CurseMaven:2.1.1'
        classpath "org.spongepowered:mixingradle:0.6-SNAPSHOT"
    }
}
apply plugin: 'net.minecraftforge.gradle.forge'
apply plugin: 'com.wynprice.cursemaven'
apply plugin: 'org.spongepowered.mixin'

version = "1.12.2-0.0.21-testbuild13"
group = "com.bewitchment"
archivesBaseName = "bewitchment"

sourceCompatibility = targetCompatibility = '1.8'
compileJava {
    sourceCompatibility = targetCompatibility = '1.8'
}

minecraft {
    version = "1.12.2-14.23.5.2838"
    runDir = "run"
    mappings = "stable_39"
    clientRunArgs += "--username=Samaritans"
    clientJvmArgs += "-Dfml.coreMods.load=com.bewitchment.core.BewitchmentFMLLoadingPlugin"
    serverJvmArgs += "-Dfml.coreMods.load=com.bewitchment.core.BewitchmentFMLLoadingPlugin"
}

repositories {
    flatDir {
        dirs 'libs'
    }
    maven { url = "http://dvs1.progwml6.com/files/maven" }
    maven { url = "https://minecraft.curseforge.com/api/maven" }
    maven { url "http://maven.tterrag.com" }
    maven { url "https://maven.blamejared.com" }
    maven { url "https://maven.mcmoddev.com/" }
    maven { url "http://repo.spongepowered.org/maven" }    
}

dependencies {
    deobfProvided "mezz.jei:jei_1.12.2:4.15.0.292"
    deobfProvided "thaumcraft:Thaumcraft:1.12.2:6.1.BETA26"
    deobfProvided "dynamictrees:DynamicTrees:1.12.2:0.9.5"
    deobfProvided "vazkii.botania:Botania:r1.10-363.119"
    deobfProvided "betteranimalsplus:betteranimalsplus:1.12.2:7.1.1"
    deobfProvided "curse.maven:rustic:2746408"
    deobfProvided "curse.maven:quark:2759240"
    deobfProvided "curse.maven:autoreglib:2746011"
    deobfProvided "curse.maven:mowzies-mobs:2699705"
    deobfProvided "curse.maven:chisel:2809394"
    deobfProvided "curse.maven:ctm:2809915"
    deobfCompile "net.ilexiconn:llibrary:1.7.9-1.12.2"	
    compile "baubles:Baubles:1.12:1.5.2"
    compile "vazkii.patchouli:Patchouli:1.0-20.99"
    implementation('org.spongepowered:mixin:0.7.11-SNAPSHOT') {
        exclude module: "asm-commons"
        exclude module: "asm-tree"
        exclude module: "launchwrapper"
        exclude module: "guava"
        exclude module: "log4j-core"
        exclude module: "gson"
        exclude module: "commons-io"
    }
    implementation 'org.jetbrains:annotations:15.0'
}

jar {
    manifest.attributes(
            'FMLCorePlugin': 'com.bewitchment.core.BewitchmentFMLLoadingPlugin',
            'TweakClass': 'org.spongepowered.asm.launch.MixinTweaker',
            'MixinConfigs': 'mixins.bewitchment.json',
            'FMLCorePluginContainsFMLMod': 'true'
    )
}

processResources {
    inputs.property "version", project.version
    inputs.property "mcversion", project.minecraft.version
    from(sourceSets.main.resources.srcDirs) {
        include 'mcmod.info'
        expand 'version': project.version, 'mcversion': project.minecraft.version
    }
    from(sourceSets.main.resources.srcDirs) {
        exclude 'mcmod.info'
    }
}