I've scanned the Proportions mod Default_AI_Research with Keno42's TechModder : there's a problem with AI trying to get Adv Mil Science 6 with only Mil Science 1 before - it should be 2 !
PvK it's time to correct this tiny error for 2.2 tomorrow ...
Note though that the way the research file works (I think), it can actually make sense to list some techs before their prereqs, in case some event (ruins or tech gifts...) give the AI a tech before it would normally research it.
Not that the AI research files in 2.1 are very clever...