Go to the BP_StaticMasterItem and create a new variable called Mesh, set it to a StaticMesh type. Then set the Replication to RepNotify and compile the blueprint.
Add the highlighted nodes shown in the image below, location at the top of the image. (The Static Mesh node is from the components panel)
Then go to the locations show in the images below and replace the node you have there with the nodes shown in the image below.
Then copy the video below in the BP_StaticMasterItem.
Then click save all in the content browser and your finished.