Update All button not working when 1 game is in the Update section

Try this

1. Head over to my Games and Apps.

2. Go to the Forza Horizon 3 game.

3. Press the Start (Menu) button, then go to Manage game.

4. In there go down to the updates section and there will be Car packs that have not automatically updated there.

Try this

1. Head over to my Games and Apps.

2. Go to the Forza Horizon 3 game.

3. Press the Start (Menu) button, then go to Manage game.

4. In there go down to the updates section and there will be Car packs that have not automatically updated there.

What happens when you go to My Games and Apps, navigate to the game icon, press the menu button and then Manage game & add-ons? The update should be listed under the Update section.

My game stats are not updating on all my games when I view them in the achievements section

You can click on Pause All if you go on queue when you update or download any games or updates. You will see on this screec Cancel ALL button and Pause ALL button.