Solr JSON Facet on multivalued enumFieldType not working

it seemed like Solr JSON facet on multivalued enumFieldType is not working. Followings are the tests that I had done.

Setup:

Solr 8.11.2 SolrCould,

<field name="multi_workdays" type="workday" indexed="true" stored="false" docValues="true" useDocValuesAsStored="true" multiValued="true" />

<field name="single_workday" type="workday" indexed="true" stored="false" docValues="true" useDocValuesAsStored="true" />

<fieldType name="workday" class="solr.EnumFieldType" docValues="true" enumsConfig="enumsConfig.xml" enumName="DayOfWeek"/>

Traditional facet and JSON facet on single-valued enum, single_workday, always works.

Traditional facet on multi-valued enum, multi-workdays, works if "facet.method=enum"

JSON facet on multi-valued enum, multi-workdays, does NOT seem to work; even with "method:enum". i.e. the buckets is always empty, like