You don't get favor for playing AIs. You do, however, get favor for getting achievements. You were probably getting the points for the 'Win a game with X' or so on and when you stopped getting them, didn't get any more.
If you need a bit more, try this:
Start a game, make the starting lvl 20, starting War Rank 10 and Filthy Rich. Play Sedna and summon yetis at the crystal till you get the award. You get the award for summoning them and getting lvl 20.
Get giants and beat the AI then do it with QoT. You should have enough then