I know .. somewhat late. I just wanted to write that I went through the same problems with reliability issues. However - I hooked the AS3595 to an ESP8266 and most libraries don support that. I modified a SparkFun lib, but had either plenty of Lightning reports even without any thunderstorm, or none with a heavy storm above.
I finally traced my problem to the proximity of the AS3595 to the ESP chip. With a clearance of about 2 inches between both, I have very few disturbers (2 or 3 per minute) . A spark from a lighter reports a disturber, using the lightning simulator (Playing With Fusion) reports a strike.
Now waiting for a real life storm.
All the posts in this thread helped me to find the problem. Thank you.
Michaela