How to build Package and Depend on Macros in Embedded Swift?

Hi! I'm just now getting started with Embedded Swift. I attempted to build the stringify macro template from Xcode in embedded mode:

.executableTarget(
  name: "MyMacroClient",
  dependencies: ["MyMacro"],
  swiftSettings: [
    .enableExperimentalFeature("Embedded")
  ]
),

I then attempt to build and run (from release mode to get wmo) and see these errors:

1.	Apple Swift version 6.0-dev (LLVM 6c1a2ac10cabb71, Swift 2a04604247a93e7)
2.	Compiling with effective version 5.10
3.	While evaluating request ExecuteSILPipelineRequest(Run pipelines { Mandatory Diagnostic Passes + Enabling Optimization Passes } on SIL for Darwin)
4.	While running pass #2548 SILModuleTransform "MandatorySILLinker".
5.	While deserializing SIL function "$s6Darwin14POSIXErrorCodeO8rawValueACSgs5Int32V_tcfC"
6.	*** DESERIALIZATION FAILURE ***
*** If any module named here was modified in the SDK, please delete the ***
*** new swiftmodule files from the SDK and keep only swiftinterfaces.   ***
module '_errno', builder version '6.0(6.0)/Apple Swift version 6.0-dev (LLVM 6c1a2ac10cabb71, Swift 2a04604247a93e7)', built from swiftinterface against SDK , resilient, loaded from '/var/folders/1j/0r1s_v0n4bn200kt9nkm9j5w0000gn/C/clang/ModuleCache/_errno-3IPVGVC1D0ACE.swiftmodule'
SILFunction type mismatch for '$s6Darwin14POSIXErrorCodeO8rawValueACSgs5Int32V_tcfC': '$@convention(method) (Int32, @thin POSIXErrorCode.Type) -> Optional<POSIXErrorCode>' != '$@convention(method) (Int32, @thin POSIXErrorCode.Type) -> Optional<POSIXErrorCode>'

Is building a macro packge (and Swift-Syntax) with Embedded supported? Are there more steps I might be missing to fix this Xcode Macro template and supported building for Embedded? Any more advice about getting started on that? Thanks!