After 20 years of great performance by Quicken (including 2 years on an M1 Mac Air, OS 11.5.2), and having reconciled 11 bank statements for new bank accounts started last summer, I get this: the most recent statement shows a reconcile error completely at odds with the previous day's reconciliation.
I uncleared the first 4 months of transactions (246 manual clicks, one at a time) and tried to re-reconcile the 1st month. Clearly, Quicken isn't up to the job!
1.) The transaction amounts match in both the bank statement and the reconcile window.
2.) The transactions in the statement are "cleared" in the reconcile window.
3.) Run the cleared transaction on a calculator and the total is in fact the statement's ending balance of $2029.10
4.) The Reconcile window reports an error of -$479.92
QED