Color by Taxonomy Term does not work when the field is using a relationship / entity ference

Problem/Motivation

Use a taxo on an another entity to "Color by Taxonomy Term" via "Event Color Overrides" included via relationship / entity reference. One easy example would be if you have a product or purchase order entity with a type taxo field and then a calendar of shipments related to a product or purchase order etc.

Note that taxo fields on the same entity work great! As an aside, it is a little weird that the default text color is the same blue as the background color.

Steps to reproduce

For "Event Taxonomy Field" choose a taxo field with a relationship on it.