This is a repeat of a posting I made at
https://community.quicken.com/discussion/7908721/how-to-fix-inability-to-link-account-to-financial-institution#latest . The problems still occurs today Friday Feb 18.
Briefly, I have 5 accounts at "Affinity Plus FCU - New", these were linked for download using Express Web Connect years ago and have worked fine all that time.
Starting Sunday, transactions silently failed to download on that one (and only that on) account. "Reset Account" either doesn't see the Checking Account or sees it and pretends to "link existing account" to it. Most subsequent updates fail silently. Occasionally, a few transactions sneak through but the balance is nor updated.
I will try "Help - Report a Problem" and understand that's just metrics and I won't get an answer. I hope this discussion yields something to try. I have tried Validation of the data file and creating a test file to connect to the credit union - that works fine for all 5 accounts (3 times).
I have not tried deactivation/re-activation of the checking account as it is currently verified for Quick Pay and Check Pay (I have Quicken Premier subscription and am up to date.)