I mean at first packed level actors would default the texture array to slot 0, but if right click and do edit the packed level actor.. (or dont use packed level actors) the custom primitive data would work correctly. Again it wouldnt when it was an instance in a packed level actor..
Keep in mind the packed level actor CPD values were correct within it. I checked. They were not set to 0 for that value.
Then i went and just toggled a switch to not use custom primitive data. It stayed on slot 0 in teh texture array even when i set the material parameter to 1 or any other value. BUT… the material preview window showed it changing even though it woudlnt in the scene… And this was in packed level actor or no packed level actor.. So basically made no sense..
Then i tried replacing the scalar parameter with a new different name scalar parameter… After that no scalar parameter conencted to the input node showed up in material instances ever again… just broke everything.. no way to get it back.