what were your other goals and calculation control options? likely it determined that the model had come to equilibrium and that's why it stopped calculating. Do some animations of data and see if it seems to converge, it might be that you don't need a full 3600 seconds.
Make sure you have "Time Depended" checked under General Settings | Analysis Type. Then in Calculation Control Options window | Finish tab uncheck "Goal Convergence" and "Maximum travels".
That worked. It took almost 12 hours to solve.