If the scene has multiple instances of an object which collide with another object around the same time, with the “Trigger Once” set, then some of the collisions are ignored.
The scene setup:
Here’s the code. NPO has a Tween behaviour attached:
The bevahiour, when the NPO collision with block is quite separate, looks like:
However, if the NPO instances are a little out of line, and collide with the block one after the other, the second collision is ignored:
My work around for this is to add a variable to NPO and set/unset it depending on whether collision is detected. Not ideal, but it works for now: