You may need to suspend your firewall to complete the Vjoy install.
Do not add Joystick Gremlin to the list of allowed devices configured in HidHide if using the XBOX ONE controller.
Carefully consider the number of buttons and axis you want to configure. Joystick Gremlin will not reload your config if you change your configuration, thus you will need delete your old config and start again.
Do not use your mouse scroll wheel to navigate the Gremlin UI, any menu drop down coming into focus will alter its setting.