Help with xbox one and metal gear solid 5,TPP

Hi, i am an older person that likes games. I have an xbox one, it is hooked up to wifi/ internet. We live in country, so internet is sketchy at best. So I've never played games online etc. Our favorite gave is Metal Gear Solid 5, Phantom Pain. The issue? I play for hours, and the game saves, but when i turn the console on, i have to start all the way from beginning. I mean, from the install. So, I've been playing the game, and leaving console on. Returning to it when i want to play. All of a sudden, screen goes black and the install screen comes back on. Now, I've checked memory on box, says 92% empty. That is the only game or anything i have on the unit. This has been happening for about 6 years now. I play for awhile, and then all of a sudden, middle of play, the unit wants to go back and install everything. I don't know much about gaming systems. That's painfully obvious. The game says it automatically saves. Whenever i "die" in game, i can restart from any check point etc. I'm frustrated, as that just happened again. Been playing for about 20 hours and now, it takes me back to install. I have always let the game install completely before playing. Please help! I have fun playing this silly little game, but want to throw the xbox out the window! Thanks!

:)