To further isolate the issue, try creating a new local user or administrator account. Just follow the steps in this link.
Let's also try uninstalling the XBox app by using PowerShell command. Right-click the Start button, then, click Windows PowerShell (Admin). Copy and paste this command Get-AppxPackage *xboxapp* | Remove-AppxPackage then press enter. You will receive a notification that you have uninstalled the Xbox app. Then try installing it again from Windows store or by using Get-AppxPackage -AllUsers| Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"} command in PowerShell.
If the above troubleshooting steps still fail, our best resort will be performing repair upgrade. Just download the latest Windows Insider Preview here and follow the steps in this thread posted by Andre Da Costa.
Regards.