Reconcile check box issues

Quicken H& B 2017 and 2020 when trying to check off a item as cleared when reconciling a checking account, the check box won't stay "checked" and the entire reconciliation window shrinks to a tab under the main screen. Usually takes 4 to 6 attempts in checking the item as cleared before the tick in the check box stays checked and the reconciliation window remains open. Typically 1/3 of the transactions required multiple "check" attempts before the item remains "checked".