I've heard of many flaws in that report, some fixed I believe. Yours is the first callout on that consideration.
I suspect that is by design, though, that they were only after end of day balances. Haven't looked at how the IRS request is worded nor would I know the accepted interpretation.
I don't see where the IRS defines "Maximum Amount", but I suppose the report only looks at the account's closing balance each day.
Will the report show the information you are looking for if you record the date the interest is paid one day earlier, or the date the money is transferred out one day later?
OK, but I don't see where the IRS asks for the date of the maximum balance, just the amount.
Ask your accountant if showing the interest one day earlier or the transfer out one day later would satisfy the requirement.
Do your bank statements show the intraday balances or the maximum balance? If not I don't know how you would get that information.
My statement (for a US account) only shows beginning balance, ending balance, deposits, and withdrawals, not even the daily closing balances. The online list of transactions shows the "Available balance" which lists debits before credits, so the balance shown is always lower than the peak.
[edit] Also - according to this definition,
https://www.investopedia.com/terms/l/ledger-balance.asp
the ledger balance is the balance at the beginning of the day, so if interest is paid and the account closed on the same day, the ledger balance would be the balance before the interest payment.