Can't add elements to Clutter Layers (Atlas Dev Kit)

I’m trying to add grass to my map by using Ground Clutter Layer Actor. After setting the static mesh and material i click the plus sign to add an element to the clutter layer. All it does is flash (as if adding one) but doesn’t add an element. At this point I am unable to add any sort of clutter to the landscape besides using foliage tool. I had no issues with this in Ark Dev Kit or Dark and Light Dev Kit.