This has happened to me twice, as a driver: a carpool ride has been agreed and approved, while driving to the pickup location, the passenger called and we agreed on a more convenient pickup location, not far away from the original location set by the App. After the pickup, both the passenger and I couldn't tell the App that the pickup has been made, and while driving to the drop-off location, the App kept directing us back to the original pickup location. Eventually the ride was not recognized as carpool and no payment made.