Creating simple interactions

I do not have UE4 opened, & not totally clear your issue. Just a shot.

Can the static mesh be hidden by default (just by playing in teh scene, before you step on the trigger), just to check if visibility works.

if you have an actual mesh in the scene, you can create a variable for it (lets call it MeshVariable), just by dragging the object (from Outliner) to the blueprint work area.

Then you should (I do not have UE4 opened so its just a rough idea)be able to drag a line out of the MeshVariable & set the visibility, then link this to the on touching tigger volume event (name not exact). Maybe give it a shot.

If it doesn’t work, maybe try make the blueprint out of the staticmesh (& maybe its own trigger volume) & try again.