Within the Xbox app, make sure you've started Xbox Streaming. Game Capture won't work otherwise.
Windows Store (UWP) games currently require extra permissions to be able to capture. If OBS is installed in the default (C:\Program Files (x86)) directory, these will be applied automatically. If you installed OBS to a custom location, you will need to add the ALL APPLICATION PACKAGES security group to the obs-studio folder.
Follow these steps:
- Close OBS if it is already open
- Right click on the obs-studio program folder, select properties, then click on the Security tab.
- Under the Groups or user names section, click on Edit...
- Click add, then type in ALL APPLICATION PACKAGES. Select Check Names and it should underline to show it was typed.
- Click OK, then Apply, then OK, and finally OK again.
- Restart OBS and attempt to capture the game again
If that doesn't work, try running OBS as Administrator.