I'm updating my mod (https://github.com/mrh0/createaddition) to Create 3.1 but having problems compiling, the cause seam to be mapping "Entity;func_213315_a(MoverType;Vector3d;)" to "Entity;move(...)" but from what I can tell, the method is already mapped to "move" ("Entity;func_213315_a" does not exist in the 20200920-mixed-1.16.3 mappings)

build.gradle:
mappings channel: 'snapshot', version: '20200920-mixed-1.16.3' // same as Create 3.1
minecraft 'net.minecraftforge:forge:1.16.5-36.0.42' // same as Create 3.1
implementation fg.deobf("curse.maven:create-328085:3260165") // latest Create 3.1

Cause:
[15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:223) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at org.spongepowered.asm.mixin.transformer.MixinTransformationHandler.processClass(MixinTransformationHandler.java:121) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at org.spongepowered.asm.launch.MixinLaunchPlugin.processClass(MixinLaunchPlugin.java:131) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.serviceapi.ILaunchPluginService.processClassWithFlags(ILaunchPluginService.java:154) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:120) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:265) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:136) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.loadClass(ClassLoader.java:352) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.defineClass1(Native Method) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.defineClass(ClassLoader.java:757) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:138) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.loadClass(ClassLoader.java:352) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.defineClass1(Native Method) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.defineClass(ClassLoader.java:757) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:138) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at java.lang.ClassLoader.loadClass(ClassLoader.java:352) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: at net.minecraft.client.main.Main.main(Main.java:118) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:644]: ... 11 more [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:668]: Caused by: org.spongepowered.asm.mixin.throwables.MixinApplyError: Mixin [create.mixins.json:StepSoundMixin] from phase [DEFAULT] in config [create.mixins.json] FAILED during APPLY [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:668]: at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinError(MixinProcessor.java:642) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:668]: at org.spongepowered.asm.mixin.transformer.MixinProcessor.handleMixinApplyError(MixinProcessor.java:594) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:668]: at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:356) [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printStackTrace:668]: ... 32 more [15:06:01] [main/INFO] [STDERR/]: [java.lang.Throwable:printEnclosedStackTrace:710]: Caused by: org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException: Critical injection failure: @Inject annotation on movementMixin could not find any targets matching 'Lnet/minecraft/entity/Entity;func_213315_a(Lnet/minecraft/entity/MoverType;Lnet/minecraft/util/math/vector/Vector3d;)V' in net.minecraft.entity.Entity. Using refmap create.refmap.json [PREINJECT Applicator Phase -> create.mixins.json:StepSoundMixin -> Prepare Injections -> -> handler$zzi000$movementMixin(Lnet/minecraft/entity/MoverType;Lnet/minecraft/util/math/vector/Vector3d;Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V -> Parse]

Try adding jvmArgs "-Dmixin.env.disableRefMap=true" to your run configurations and switching to mixed mappings, like i do for cogwheel tweaker