The “Great Negotiators” pack has been released, you can find all the changes here. Right now there are various issues though, including many users reporting that their game has been re-set, and that no DLC is available, or that only the free Julius Caesar is available. Firaxis has already released a new patch, which will hopefulyl fix these issues. You might need to restart Steam and/or your computer, and in case this does not work, then wait for a while, and be patient. Please note that the Leader Pass is for free if you own all the other DLC. It may show up still for buying right now, but this is a bug, please do not buy it, wait for this to be resolved by Firaxis. For progress on the technical issues please check here.
In case you have issues with unlocking Caesar, please have a look at this video.
In case you want to watch some streams until all the issues are fixed, then please have a look here.
