Odd.....I can't even see or find a logical reason for light strikes. It's like the striker is being released to early in the cycle. I haven't paid attention (something about looking at the sights instead of the striker indicator) to the indicator when I get light strikes.
If you hold the slide upside down and hand cock the striker to where the firing pin is brought back into its first detent after slide is cycled and then depress the plunger this may give you the result of a light strike.
If you hold the slide upside down and hand cock the striker to where the firing pin is brought back into its first detent after slide is cycled and then depress the plunger this may give you the result of a light strike.