The core format of the Condo.dat file has never been changed as I recall, but we started using Steam Cloud to save that file for you now instead of it being saved locally. Sounds like something went wrong with that process or it did not work.
If you go to “C:\Program Files (x86)\Steam\userdata\########\394690\remote\Condos\C_Condo” (where the “########” is dependent on your Steam ID), you can rename your previous Condo.dat to CondoData and overwrite the one in the folder. If it doesn’t exist, you probably have to launch TU and place an item in your condo first.