More details, please.
Which bank name have you been using in the past and which of the ones below have you tried?
What happens when you try to use the Add Account process ("+" icon in the Account Sidebar title)? What error messages or error codes do you get?
I am having the same issue, has not updated in a year, seems to be when they changed to lowes.sf.com from the main Synchrony path. My current account settings are trying to go to Synchrony but I cannot seem to find a way in Quicken to point to the correct one. Is the only option really to close the account in quicken and add a new one? I have years of history here in this account, does not seem like a reasonable solution.