Additionally, with the latest version installed, Oculus OpenXR doesn't work either (even though Oculus is set up as the default OpenXR runtime). Uninstalling VivePort and related software immediately fixes those issues.
@Dario We're experiencing the same issues in UE4.27. Everything was working fine on the beta branch for a while but now we don't get any input events through. Furthermore the system seems to never report it's focus state causing our application to not progress al together.