Go to the BuildPreview bp and change the target of the node shown below to the selected mesh component, location shown at the top of the screen shot.

Then go to the Get Overlapping Actors function and make the changes shown in the image below.

Go to the Set Build Type collapsed nodes and make the changes shown below.

Next go to the Collision function and change the input of the highlighted node to disabled.

Next go to the Create Foundation Grid function and add the highlighted nodes shown below. Make sure you do this on the second loop in the function not the first.