high sierra issue

[grimmwerks]

Whenever I add motion-yaml to a project -- either rubymotion vanilla or generated by redpotion -- I get the following error:

/Library/RubyMotion/bin/gen_bridge_metadata:16:in `symlink': Permission denied @ rb_file_s_symlink - (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain, /Applications/Xcode.app/Contents/Developer/Toolchains/OSX10.13.xctoolchain) (Errno::EACCES)
	from /Library/RubyMotion/bin/gen_bridge_metadata:16:in `<main>'
rake aborted!
Command failed with status (1): [RUBYOPT='' '/Library/RubyMotion/bin/gen_br...]
/Library/RubyMotion/lib/motion/project/xcode_config.rb:476:in `gen_bridge_metadata'
/Library/RubyMotion/lib/motion/project/vendor.rb:242:in `generate_bridgesupport'
/Library/RubyMotion/lib/motion/project/vendor.rb:175:in `build_static'
/Library/RubyMotion/lib/motion/project/vendor.rb:48:in `block in build'
/Library/RubyMotion/lib/motion/project/vendor.rb:47:in `chdir'
/Library/RubyMotion/lib/motion/project/vendor.rb:47:in `build'
/Library/RubyMotion/lib/motion/project/builder.rb:68:in `block in build'
/Library/RubyMotion/lib/motion/project/builder.rb:67:in `each'
/Library/RubyMotion/lib/motion/project/builder.rb:67:in `build'
/Library/RubyMotion/lib/motion/project/app.rb:78:in `build'
/Users/grimm/.rvm/gems/ruby-2.4.0/gems/motion-cocoapods-1.9.0/lib/motion/project/cocoapods.rb:54:in `build_with_cocoapods'
/Library/RubyMotion/lib/motion/project/template/ios.rb:69:in `block (2 levels) in <top (required)>'
/Library/RubyMotion/lib/motion/project/template/ios.rb:179:in `block in <top (required)>'
/Users/grimm/.rvm/gems/ruby-2.4.0/gems/rake-12.3.0/exe/rake:27:in `<top (required)>'
/Users/grimm/.rvm/gems/ruby-2.4.0/bin/ruby_executable_hooks:15:in `eval'
/Users/grimm/.rvm/gems/ruby-2.4.0/bin/ruby_executable_hooks:15:in `<main>'

In the /Applications/Xcode.app/Contents/Developer/Toolchains/ there is only XcodeDefault.xctoolchain

Not sure if this is a High Sierra / Xcode 9.1 or Rubymotion 5.5 issue.