Cascade: Framerate change in SubUV movie using a random starting frame?

Hi everyone! I’ve got a looping spritesheet animation that I’m using in an effect I’m making. Since the animation loops, I’m using the SubUV movie module to control it’s framerate during the animation.

Currently I’ve set it up using a constant curve with the framerate being set to 24 FPS at 0 and 12 FPS by 1. This works fine when I try it - The framerate starts at 24 FPS when the particle spawns and then steadily slows down to 12 FPS at the end of its lifetime - but when I try to randomize my starting frame by setting the “starting frame” parameter to 0, the framerate appears to break completely and “jump around” during the effect.

Does anyone know how to fix this?