I'm not sure how this all happened but something really strange happend when I was playing ERE.After long and hard campaign I had ERE down to one settlement :





Couple of turns later the time has come for final assault.I managed to take take Pergamum only to see this :



I have tried to play again ( save point) and waited 6 turns for city to surrender with exactly the same effect.Perhaps removing "shadowing empire_east" from descr_sm_factions would make the difference ?