All Households Suddenly in the Gallery Instead of their Lots?

So, I'm not sure when this issue started-- some time in the last week, most likely, but all of my families except the most recent one I've played seem to have booted out of their houses. Help?

I have been playing with a new family in Windenberg for the last week or so, after getting the Get Together expansion.

Tonight when I decided to switch to a family in another neighborhood (I'd had several other families I was playing in previously in Willowcreek and Newcrest), I discovered that all of my other houses were missing! All of the families seem to have been sent to the gallery and reset, with no evidence of ever being played (at least one character who died of old age is back with his family). 

Could this have happened when I got the expansion pack?

Is there any way to get them back to the way they were? If not, it's a lot of hours of game play lost...

• Are you using mods: Never
• Are you using custom content (as in clothing and objects) ? No
• Did you try a new game for testing purposes to see if you can duplicate the issue ? N/A
• What is your Operating System (XP, Vista, Win 7, Win 8, Win 8.1, MAC) ? Win 10