Opening Balance error

The amount entered for the begining of the financial year in opening balances is correct and as per the actual bank statement. Bank reconsiliations carried out 3 monthly and were correct up until 31 March 2023.

Now however all have needed to be undone as nothing now reconciles. When checking the opening balnce for the financial year a message appeares:

Amount left to be allocated xxxxxx which is short if the actaul opening balance.

Tried reconciling June the last financial year to the actual opening balance and that is vastly in a negative.

This is the first financial year this file has been in use - opening balance and June 30 should be the same amount.

Any ideas?