I've encountered the same bug, but I think I can add more information.
(I play hotseat by myself, so no transfering save files to other computers)
I think this bug may have to do with the number of human players in hotseat mode. In one game, there were 4 human players and 18 AI players, and after I agreed to declare war in ten turns, the AI never asked me to fulfill my promise.
In another game there were 10 human players and 12 AI players. After I as player1 agreed to declare war in ten turns, I was asked to fulfill my promise on the next turn of player1. It's as though playing other human players' turns count towards the DoW in 10.
I think the reason that the AI did not ask me to fulfill my promise to DoWin10 in the game with 4 human players is because 4 is not a multiple of 10.
In the same game with 10 human players, I've seen an AI declare war on me, and ask for peace the next turn.
I've also encountered games where the AI asks way too often for a DoF.
Like I've said, I'm not sure if this happens only when playing as different human palyers on the same computer, but I suspect that the root of the problem is with the number of human players in the game, and a bunch of diplomatic agreements are affected by it.