I think I found a glitch where if a member of the over/undercouncil is killed, they can no longer vote(obviously) but they still count as a member. If enough members die, it can make it impossible to pass anything, since there might only be 3 living civilizations of a 8 member council, so there is no majority even if there is a unanimous yes vote.
Good catch. This is probably the solution to an 'open' mystery here. See post 3338, #20, where overcouncil resolution being difficult to pass was reported before.
Best wishes,
Breunor