Open YuneecPilot app and tap on the “head and shoulders” icon at the top right. Sign in if you haven’t done so already and you will then be taken to a screen with Flight Records, Last Location, and App Feedback.
Last Location should have the telemetry from the Mantis Q’s last known location. You also need to contact Yuneec CS about the “flyaway”.
This sounds like the Mantis lost or never had good GPS and drifted off with the wind. If GPS is not good the Home Point won’t be recorded and the auto RTH on connection loss cannot occur. Did you happen to try doing a manual RTH to try and bring the Mantis back?
If the Last Position doesn’t work, refer to the sticky post here that covers retrieving the telemetry and upload it here to see if we can trace the last flight.