In this instance, I have just finished constructing a settler, and I'm unable to select another unit/building for production. The supposedly completed settler is nowhere to be found. In the image below, you can see that there is nothing in the production list; I can't build any units, buildings, wonders, or "other". the "-" minus symbol indicates that clicking the header would minimize the list (clicking it simply shows the plus sign).
SHIFT + ENTER wasn't working for me, so I can't seem to progress in this game. I've tried reloading a save file from the beginning of the turn. I moved my single garisoned unit out of my city, and that didn't fix anything.
Has anyone seen this before, have any idea what could have caused it, or know how to fix it?