First go to your project settings, then to the collision category and press the New Trace Channel button. Name it Grid and press Accept. It should look like the image below.

Then go to the BP_MasterGrid and select the highlighted node and copy the collision settings in the image below.

Next you will need to go to all the trace nodes show in the images below and change the Trace Channel to Grid. The locations of these nodes are shown at the top of the screenshots.

To find the nodes quicker you can use Ctrl + F and search for the function name.

Next go and select the components in the components panel shown in the images and copy the collision settings shown in the details panel, If you do not see the tick bot options for the collision settings make sure you set the Collision Preset to custom. Location are in the centre of the event graph view.