At the main menu, there is a large thumbnail of the sims family and smaller thumbnails of the lots.

Some of my lots show thumbnails and some of them are blank.

Does anyone know how to fix it?

If you have WA installed there is a bug where the saved game thumbnail in the main menu is blank if you have placed a tent in a chest. Strange but true. If you go back into the game, remove the tent and save again the thumbnail will return to normal.

The saved game thumbnails can also be blank if they used a neighbourhood that is no longer installed in your game.

Found all the tents, sold same. Problem solved.

Thanks a lot, I never would have found that without your help.

That is one strange bug...

Is there a way you can manually change the thumbs?

Thank you for this answer! This problem has been bugging me so bad for so long!

Thank you, Simbalena. I've been googling for an answer for three days now. I was so worried that my lot was corrupted and possible the family too. It's a relief to know that it is caused by a one single tent in a chest. I was already prepared to move the family and destroy the lot. Saved by the bell. *Sighs deeply*