When enabling Cross-Save, instead of choosing your Xbox data as your main Cross-Save data, as it asked you to do, you chose your Steam save data. After going through the process, you then confirmed to the system that you wanted to use your Steam save data across all connected platforms. The instructions asked you to pick the account you wanted to use everywhere, and you chose Steam. Because you chose your Steam save data as your Cross-Save data, every platform you log in with that's connected will show your Steam characters. Your Xbox data was not erased; it has been stored safely away while you have Cross-Save enabled with your Steam save data. Because you chose the wrong account for your Cross-Save (Steam instead of Xbox), in order to fix it, you must first disable Cross-Save and accept a 90-day security lockout period before you can reenable Cross-Save; you can still play the game on each platform, but during that 90-day period, you cannot enable Cross-Save again. After disabling Cross-Save, your Xbox characters will reappear when you play on Xbox because they were simply stored, not deleted. After waiting out the 90-day period, you can reenable Cross-Save, and when you do, please make sure you choose the correct account as your main Cross-Save data. Before clicking the button to confirm and enable Cross-Save, please read the setup carefully to insure you have the right accounts set up the way you actually want them to be. If you enable Cross-Save and then have to disable it again, it will lead to another 90-day wait, so it's best to double check before you click the final button to turn on Cross-Save instead of after.