I am using ASN 1.0.5707 with Prepar3d I 2.5.12946 and have been flying around New Guinea and nearby Indonesia. I frequently see lightning within modest cumulus clouds (to to bottom of cloud). These are ones with no rain and which appear to be no larger than a few thousand feet in size both horizontal and vertical. I have seen this with 20% or less sky cover and no CB or TCU around.