Hello Walter, I have been experiencing this same issue. I have optical flares installed in After Effects CS6, and I can add the effect to the layers and edit the properties. However, the flare itself is not visible at all in the screen. I have tried enabling and disabling the use GPU property, and nothing happens. I also deleted it and installed it again… same behavior.
The strangest fact is that the first time I tried adding optical flares effect, it worked. After closing the project and opening it again the following day, the flare was no longer visible.
Any ideas on what can be happening and how to solve it? Thanks a lot for the help and urgency!