EmVeBo
This exact same thing happened to me last week when I noticed the game version had reverted back to 1.111 in the main menu, no idea why. I fixed it by renaming the Sims 4 folder in Documents > Electronic Arts then launching the game so a new one was created. The main menu then showed the current version of the game so I started a new household and placed them, went into BB and all the items were once again back in my game. Try that and see if it helps. You can move your saves, tray etc into the newly created Sims 4 folder if all is well.