Having tried inkmerable times to get MSFS 2024 to start on my Xbox X.
Here is my solution:
View the MSFS2024 icon at the main menu
Select it and pass the ‘hamburger’ button next to the X on the controller
Select with ‘A’ the Manage game and add-ons
Select the Saved Data option bottom right of screen
Select the Reserved space option mid screen
(DO NOT use the [DELETE ALL0] option, as when I tried this it didn’t help.
AFTER this and selecting MSFS 2024 from the main menu it started perfectly
I’d be interested if it helps others.