We are aware of an issue that will not allow your manually entered flights to save. The system seems to lock up when you first go to add an expense, and rather than saving or hitting cancel, you hit Dashboard or another page link at the top. If you then try to enter a new flight from the Flights page, it locks up on you and won't save.
A fix for this is being worked on, please let us know if this happens to you. To avoid the issue, either save or cancel your expense before leaving the page.