Using Cascade Constant Curves to control particle values for times longer than 1 second in emitter duration results in a bug. The value clamps at one second, and freezes at that value for the remainder of the emitters duration. Example:
A 3 second emitter has:
In this example, the emitter uses the value delivered by the curve at the 1 second mark, and continues that for the remainder of the emitter’s duration. Here are other reports of this problem in case my explanation doesn’t resonate.
This is a report to call more attention to the issue as it hasn’t been fixed in 4.9 or 4.10, and as an FX Artist it is vital to have control over particle emitters past one second in duration. This is also here to clean up everyone’s search for a solution.
THIS IS THE WORKAROUND:
Simply change your constant curve to a parameter, make your particle emitter a component of a Blueprint actor, and set the particle’s parameters in the Blueprint. You can essentially export the whole curve editing process into Timeline in Blueprint, which in my opinion is a bit better.