Same Issue here. Has happened on multiple saves. Here is one that happened repeatably on turn 102. Ming Turn 102.ctr

I restarted a new game, with completly others choices, and I have the same issue. Save and reload the game seems to do the trick for a while but the issue come back after a few turn.

It seems to be linked to Shared Projects ? On my first game, it started on the completion of the cultural wonder, Notre-Dame, and on my second game it started when I was finishing the holy site, Stone Rings, both as a Shared Projects.