Resources were showing up in the 'external' content. For example, resources external to v2 (such as v3-trigger event) were present in the external content area. Additionally, resources with no content were still present in v3 (such as v2-0962) and it is also external because v3 references it.
This spreadsheet fixesForExts.xlsx outlines resources that were moved in the clean up of this external content.
The current rendered view of external resources is available at https://build.fhir.org/ig/HL7/UTG/codesystems-external.html