Thank you. I didn't uninstall my game but I tried reset and download save data. It works so far.
I didn't try this saving method because the last update makes the game look different. I could see the download button before, but now you have to reset before download option appears.
Anyway, I didn't realize you were the OP. I don't know why I can't add you. My gamertag is schathach. And I am a girl by the way, although I don't mind being called as a guy on internet since it doesn't matter lol
Just FYI, you can change your gamertag through xbox.com (so it's easier to remember). I had a problem with changing name via xbox app so I had to use website.
I don't know if it also works for you. I don't reinstall, but simply saving, reset, then download each time my sims don't continue their last actions.
Basically you manually upload your game data to cloud (the game won't save it for you). Download option only appears if 1.) you are on new device or 2.) you reinstall/reset your game. On both cases, the game doesn't have any game data, thus it will prompt you to start a new game, unless you've played before and store the game data on cloud. If you've saved it, the game will automatically detect your game data on cloud and offer you to start from saved data instead.