Forza Horizon 5 Installs then Xbox App says its not installed

No. When you go to the Forza Horizon 5 page. It says "Install from Xbox App"

I've signed in on the new account and installed the xbox app and signed in on the other account on there and forza horizon 5 is not on the installed list

Hi MintyyCold! My name is Ricardo an independent advisor ready to help you with this situation!

This could be happening due to updates as have been some rolled out, but you can also try this

Step 1: Open the Settings app. This can be done by clicking its icon in the Start menu or simultaneously pressing Windows logo + I.

Step 2: Click the Apps category icon and then click Apps & features to see all installed apps as well as classic desktop programs.

Step 3: Click on the app that you want to reset to see the Advanced options link. Click on the same (advanced options link).

Step 4: Finally, click the small Reset button. When you click the Reset button, you will find a small dialog box with “This will permanently delete the app’s data on this device, including your preferences and sign-in details.” Click the Reset button in the opened dialog box to reset the app.

Step 5: Once the Reset is done, you will see a check sign next to the Reset button. And restart the Pc

It says you own forza horizon 5, click here to install, takes me to the app, but afterwards same thing happens as usual.

This is what helped me and got Forza to download.
1. Go into the Microsoft Store and search Forza Horizon 5 Standard Edition.
2. Next you want to click on Forza Horizon 5 Standard Edition and you want to click Install from the Xbox app.
3. This will take you to the Xbox app and when it takes you to the Forza game scroll down and look at the tab named "Included in this bundle" And click Forza Horizon 5.
4. This should take you to the regular Forza Horizon 5 game rather than the Standard Edition, And then you want to click install and this should download the game.

Hope this helps have a good day!