Specific to the Blueprint Construction Script, Local Variables cannot have their value set in the Editor, because the "Default Value" section of the Details tab will never appear. This only affects Local Variables in the Construction script.
Result: Default Value is missing from the details panel upon compile.
Expected: Default Value would populate the details panel upon compile
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-80562 in the post.