Dbuffer Decal materials don't render correctly when applied to a decal component in a blueprint. You can compare it to the decal actor and see that they aren't visually the same despite having the same settings and material.
You can test all the different Dbuffer blend modes and note that there are a few errors. In most cases the decal component in a blueprint will appear mostly black even when a blend mode without color is selected.
You will see a deferred decal actor and a blueprint actor with a decal component using the same material. The blueprint decal doesn't display correctly.
Both the decal actor and the blueprint decal component look identical.
Head over to the existingAnswerHub thread and let us know what's up.