All finish can act up when it is too cool. Careful on thinning krystal...at least without using there thinner. Ml cambell suggests spraying as is and to refrain from more than three coats. I know a bowyer who thinned his Krystal (don't know with what but it wasn't krystal thinner). On the first rainy day he displayed them, they all developed a foggy appearance that didn't go away.
If you let most any finish get too thick on a flexible object such as a bow, it has a tendency to crack (not noticed this with buffalo hide/aka tbird).
I am unfamiliar with a Preval gun as I use an automotive gun. I also heat my spray booth to about 75-80 degrees (shop temp is set at 72 usually)
As I have had no complaints on the Krystal (all new and fresh), I would be assured that the temp was the culprit.
good luck, bigjim