I guess a follow restriction is missing.

Fragment is ambiguous: amb([[I,I,I], [I,Label("II")]])

in

  name resolution
  
    labels
    //D // definition
      I // import
      II// lower priority import
      P // parent

    order
      D < I,
      D < II,
      D < P,
      I < II,
      I < P,
      II < P

    well-formedness
      P* . (I|II)*

Ast:

          [ Labels(
              [ amb(
                  [[I(), I(), I()], [I(), Label("II")]]
                )
              , P()
              ]
            )

Spoofax version:

Eclipse: org.eclipse.platform.ide 4.6.2.M20161124-1400
Spoofax: org.metaborg.spoofax.eclipse 2.2.0.20170207-125653-master
System: Mac OS X x86_64 10.12.2

Submitted by Daco Harkes on 8 February 2017 at 14:16

Fixed in the latest build.