Xbox One forcing me to reinstall a working game

My region is set to the U.S, I downloaded the game using a disc sent from the US as well. I've never had this issue, hopefully it's just an error and fixes itself

A hard reset may solve this problem.

Hold down the power button until the system shuts down and unplug the power cable.

Wait for 5 min and plug it back in and restart the console.

Is it showing an error when you try to start, or just showing up in "Updates" section of My Games & Apps? If it's a patch, then, depending on how the game was developed, it's possible that the patch required a full re-download of the game. Sucks, for sure
I know, and I don't think there is anything to do about it, except maybe make friends with someone in Signal who can hook you up?

I had been thinking about it recently, I was in a similar situation a decade ago, but the Xbox 360 was a lot easier to handle when offline on deployment, and I thought about how bummed I would be trying to get a Xbox One to work w/o regular reliable internet.
The 360 was so easy to cart around with me and hook up wherever I found myself.

I talked about it some here, as an Xbox Ambassador, which is a program you might want to look into.

What I might recommend is reaching out, you can message me if you want to talk about it, into having the content downloaded state-side (or OCONUS or whatever your home station is) loaded on to an External Drive and shipped back. If you swapped drives back
and forth through postal you could have them up to date and such on a regular basis, and only have to connect to authenticate ownership. It would take a bit longer going mail wise, likely, but would be less precarious than the setup I can only imagine you
have to get that thing internet to download over a week.

That's really strange, it should only have you download an update, not the entire game again. Have you changed your Region settings on the console, since you are deployed and might now be in a new Region? If so, I wonder if it's not recognizing the game
in the new Region you're in and it's trying to make you install the correct Region version of it?

Was there an update for the game, and did you cancel it?

If so, then that may be why you have to reinstall the game. After selecting "Cancel all", there should've been a prompt that says:

Clear the queue?

Canceling installations and updates might uninstall the items in question. Anything being moved or copied will remain in its original location.