Hey, I had a very similar issue on my mac and I was able to fix it. While it’s not guaranteed to be the same issue, this sounds pretty similar to a known issue that Civ IV has with mods post-R&F.Now, unfortunately the fix works a little differently on Mac OSX due to how the game's files are stored. You'll want to download the fix as normal and extract it to anywhere easy to access. Then you'll want to follow these instructions from the above forum: "go in 'Your Library' on Steam, right click on Civilization VI then choose 'properties', then 'local files' then 'browse local files'". Here's where things change for Mac users.You should be in a folder with 3 items, including "_CommonRedist", "Civilization VI", and "DLC". While the fix indicates you should replace the files within this DLC folder, that does not work on Mac, believe me. Instead, right click on the application (labelled "Civilization VI") and click "Show Package Contents". You should now see a folder with several different options, go to the folder "Assets". Withinfolder is another "DLC" folder, and this is the one you will want to install your fix. Take the files from within the fix folder and drag them into this second DLC folder. It will prompt you to replace files several times, allow it to.After you've replaced each file, you might well be done. Start the game and see if it still boots you back to the main menu when you have the mod enabled./Library/Application Support/Steam/steamapps/common/Sid Meier's Civilization VI/Civilization VI --right click->Show Package Contents--> Contents/Assets/DLC(ALSO shoutout to Gedemon for putting me in the right direction)