Hello there, I have encountered this issue as well. Luckily there is a simple way to fix this. Set the static mesh component inside a trap to either stationary or movable. When you do the mesh becomes visible again. It is only invisible when set to static - I dont know what causes this, must be a bug after a recent update.
TIP: If you have multiple of these you dont have to select each one individually. You can select all of them and then from context menu choose "Edit Components in the Property Matrix → BaseBuildingStaticMeshComponent.
Hope this helps 