After reading through the thread I've still no answer to my problem:
Setup D-30 artillery using the wiki and the example missions as a guide to see how everything works together. Got them to fire through the SECOP manager, yet no explosions.
They correctly point and shoot, I get radio messages saying: "Shot" as well as "Splash" from both HQ and the Player. But no explosions on the target location.
I tried standing pretty close to the target zone so it's not a graphical error. I hear no explosion sound nor is anything destroyed/killed.
Any suggestions?
EDIT: I've just put a pair of GRADs up to fire at anything entering a Trigger zone, they work fine on my map.
EDIT 2: Okay seems moving the artillery has fixed the problem. Odd since I made sure to give the arty a clear line of fire so that the shells did not hit anything. I had placed the artillery up on the hill where base Manhattan was in the SP campaign. Perhaps it hit the top of the world? :P