Halo 5: Guardians is a massive game in terms of its hard drive footprint, so it helps that people who pre-ordered a digital copy from the Xbox Games Store can download the title ahead of time. But developer 343 Industries warned recently that some pre-order customers may have unknowingly downloaded an "incorrect stub file" instead of the actual game.
The issue applies to some individuals who pre-ordered Halo 5 before Sept. 21 and who have disabled their Xbox One's "Instant On" power mode (aka the mode that supports Kinect's "Xbox on" voice command). Those who pre-ordered on or after Sept. 21 should be good to go. 343 Industries said the issue should only affect "a small number of players."
There's an easy way to check. Head to the Xbox One's "My games & apps" screen and sort your installed games by size. If the Halo 5 installation takes up more than 40 GB, you have the correct version of the game, and you'll be able to download further updates as they become available. If the installation is smaller than 40 GB, then you're one of the unlucky few with the placeholder stub file. In that case, you'll need to delete that file and re-download the game.