Unless it was changed, you should be forced to accept any AI peace offer once you are fully occupied.
In addition, the AI will be more willing to accept peace deals the longer the war is going on.
Anyway, might be worth a bug report if it is in the release version.
In addition, the AI will be more willing to accept peace deals the longer the war is going on.
Anyway, might be worth a bug report if it is in the release version.