[GNC] Recurring Reconciliation Problem after Gnucash 3 upgrade

[Peter Jackson]

A few months ago after upgrading to Gnucash 3 on Windows 10, I noticed on several accounts that a few previously reconciled items (ie from prior months) had lost their little  "y". In all cases but one, I was able to correct this the next time that I reconciled the accounts.
However, in my main bank account, I have one old item (June 1st) , that remains unreconciled. The bank balance is correct. The opening and closing balances on the statement are correct, but if I try to reconcile this item, I am out of balance, ie no zero.
This is just an irritating anomaly, because each time I reconcile, the item shows for attention. Any suggestions please...
Peter