List property ordering - mixed index not used as expected

Hi All, Using JanusGraph 1.1.0, it seems that mixed index is not used when order().by() step is used for a property with LIST cardinality. I have tried both with Lucene and Elasticsearch index backends and with none of them the index was used for sorting. For single cardinality submissionDate4 property, it seems that mixed index is utilized for sorting as seen on single property - index used for ordering.png enclosed. When I created the same submissionDate4 property as list, the ordering is done by OrderGlobalStep as seen on list property - index not used for ordering.png enclosed. I have also enclosed how the graph and schema were created: 1. for single cardinality property see enclosed single.groovy 2. for list cardinality property see enclosed list.groovy Could you please help pointing me to the right direction what I am doing wrong with the list property indexing? Thank you.

single.groovy

list.groovy