After you exit the program, before shutting down, mouse-over the Steam icon in your system tray.  If it says "Synching", don't shut down yet.  Once it no longer says "Synching", then it's done uploading your save games.  The transfers are slow and LH's saves are big, so it can take a couple minutes.

I've had the same problem since I play at home on one computer and at work... er, I mean, at other places, on a different computer.

Stardock, could you stop saving tiles in the savegame, as the tiles' looks don't affect functionality?

https://forums.elementalgame.com/446697

I'm pretty sure Steam handles the synchronization, and Stardock has no control over that aspect.  When you quit the game, mouse-over the Steam icon in your system tray and see what it's doing.  It may have gotten stuck synchronizing, or if you were doing torrents or something there may not have been enough bandwidth to upload the save games in a half hour's time.  The save games are quite large, and torrents can cut your Steam synchronization down to 10-15 KBps.

As for when it occurs, it begins synchronizing within a minute of closing the program.  You can actually tell that it's synchronizing by looking at the system tray icon, because it'll have dots at the top.