Bank reconciliations are not guaranteed to go smoothly. When they don't, users need to leave the reconciliation to make/change entries or are called away for other necessities interrupting the process.
SAGE50 is designed for a perfect world. Leaving the Reconciliation assumes the account is reconciled and the items selected. Returning to the Reconciliation launches reconciliation for the next period.
Items that have been marked, though not necessary actually reconciled, are reported as if they have actually been reconciled, creating a state of confusion where items are reported as reconciled, indicating the period has been reconciled when this is not necessarily true.