The Account Balances report under Report > Net Worth & Balances is giving me wrong security balances in just 1 of my 4 investment accounts. On the actual report page, the Date Range is set to Last Month and the Interval to Month. Under Customize, I've checked the Cents and the Account Detail boxes and am looking only at my 4 investment accounts and all non-hidden securities. 3 of the 4 investment accounts show correct numbers (i.e., they match what's showing on the Investing tab and the values differ from the end of the previous month and the end of last month). But, in that final investment account, most of the securities show no change in value over the month and the value at the end of last month is wrong (i.e., it doesn't match that date's value on the Investing tab). Oddly, I've got one security that's in that "bad" account and another "good" account. The report show the correct values in the "good" account and an incorrect value in the "bad" account. Even odder, if I change the Date Range to Include All Dates or Last 12 Months, the report is correct. Switching back to Last Month and it's wrong again.
I've just finished a Reconcile to the statement for last month and everything's correct. There are no Placeholders, no odd transactions, no Unidentified Securities and I've gone through all but the final File Validations (no problems found).