I enacted the military civic called Paid Wages. The description says +20 stability on city that you occupy. I was in war, occupied two cities that were both near 30-35 stability but neither of them displayed the +20 bonus from this civic. (all it displayed was the default - +40 base value etc)  I moved military units to the city center, waited a few turns just to make sure but made no difference. For reference, I was playing the Persians (so Cyrus's +10 stability did show up correctly) on the remote possibility that there is a conflict of some kind..