Problem with 1.4's weapon collisions?

I noticed that in the 1.4 release, weapons dont seem to be displaying their "on::collision" particle effects properly. This occurs in Stock 1.4 without any changes. It happs with the rocket launcher from the Tutorial.base tutorial, (which I am using as a base to put in my weapons) and also the crossbow in the starter.fps example.
These weapons both work fine in 1.3, and when I port them to TSE, the explosion effect displays perfectly too.
The on:collision functions are being called, when my rocket hits an object, it prints a message to the console saying its on:collision has been called, but I dont see the explosion particle effect.
I see the light spot that is emitted and that follows the arrow/rocket, but no explosion.

I would imagine this is a 1.4 bug, since it occurs in completly unmodified code. I am assuming that since noone else has posted about this, its a simple error, and I could probably fix it myself if I had a list of what code has changed from 1.3 to 1.4?
I assume its just a line or two thats different, but I cant find any documentation or sample code that shows how 1.4 differs.
I'd appreciate any pointers or anything anyone has?
JS