The input paramter is a type of UEdGraphPin. The PinType.PinCategory can be softobject or softclass, and the reference path is saved in a paramter named DefaultValue of UEdGraphPin.The DefaultValue is a FString, so the cook process can't find the reference of this pin.
I modified some code to fix this issuse as below.
The Blueprint will not be cooked out.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-78022 in the post.