I had a deal with Elizabeth where I gave her 7 coal/turn in exchange for 16 gold/turn. For some reason, starting on turn 373, it keeps saying Deal Ended, and gives me my 7 coal back. However, it does this continuously until the deal actually runs out (after 30 turns). I ended up with 77 coal. Elizabeth only has one city, and is at war with Bismark. I loaded the autosave (attached) and tried trading the coal as it came in. I could trade it, and that didn't stop the coal from coming in.
The save is after I got the deal but before the coal starts accumulating. That starts at turn 373.
I have version 1.0.0.20