[Play 2.6 - Scala] How to handle List[E#Value] E <: Enumeration in play-json?

I have a case class with an Option[List[Enumeration]].

No instance of play.api.libs.json.Format is available for scala.Option[scala.collection.immutable.List[scala.Enumeration.Value]] in the implicit scope (Hint: if declared in the same file, make sure it's declared before)

How would I go about resolving this?