(EntityFieldQuery: Taxonomy term cannot consistently sort by term weight

Term weight is stored within Mongo "taxonomy_term" collection. Taxonomy term weight appears as a sort field available from within an EFQ Taxonomy view.

However, Term Weight is not consistently prevailing in sort. At times "last updated" (default sort if no sort is selected) overrides sorting by Weight. For example, in a list of term where weight is 0-9, sorting by weight returns: 7 5 1 0 8 2 3 4 6 9.