The class org.modeldriven.fuml.assembly.ElementAssembler was changed in commit 5041078 to update the handling of XMI external references. However, part of the assembleReferenceFeature code dealing with XMI internal references for collection features was also changed. This change re-introduced a bug in which certain XMI references cannot be resolved during incremental loading (for instance, if an action within an activity references a class defined outside of that activity but within the same XMI file, as part of a collection).