So my testing strategy was to choose a graphics setting in Ouroboros, then head to RWZ and power analyzer a Pylon. Apply sleet, taking an image right after application, and then another image after 16 seconds or so. Continue until the bug occurs (or I've tried so many I don't think it will occur). I repeated this first for Ultra settings, then Recommended, then Minimum, the Recommended again, and finally Ultra again. Results:
Ultra run 1: First Sleet worked, Second bugged
Recommended run 1: First Sleet worked, Second bugged
Minimum run 1: All Sleets worked (kept going until 12)
Recommended run 2: All Sleets worked (kept going until 12)
Ultra run 2: All Sleets worked (kept going until 12)
My guess is that there's something else going on which just makes all the Sleets work for some period of time after whatever it is happens.
Some images, first from Ultra run 1: