When Synergy imports ALT data, it also imports band information for borough schools. If these bands have not been assigned a hierarchy for all school rounds, you'll see this error when attempting to amend any school information.
To resolve this issue, follow these simple steps.
Open the school record, then click the Admissions tab.
Set Filter Round By to All Rounds, then add band hierarchy to all rounds that have a band assigned to them.
Click Save.