OK, I quickly tested with the same save file I posted to help you find the bugger, and after hitting Next Turn, behavior seems back to normal: notification for deal expiration, counters correctly reset, expired deal appears in the diplo window with correct turn dates. Great!Tech curiosity: what was it?On a secondary note, I noticed that some deals without expiration appear in the diplo window (Embassy deals, which appear as expired even though they don't and are still valid). Also, I had one resource deal cancelled due to a DoW against me, and the expiration date was set to what it would have been if normally expired, not the real DoW date. Are these related to the previous bug?Thank you so very much for making it savegame compat!