I had the same problem, and I found the solution. In the account that you are having problems with, go into "Edit Accout Details". Select the "Online Services" tab. Select "Reset Account" and follow the directions from there. I did this for may bank\checking account and credit card account with a different bank and it downloaded the missing transactions in both cases. I think the connections somehow got corrupted, and this appears to have fixed the problem. Hope this works for you.
Sorry, I just noticed you tried account resets and they didn't work. Please disregard my last post.
@BarryMo - unfortunately, there are multiple potential points of failure, so hard to tell what the issue is. Is the problem the FI server isn't running properly, including failure to load all the transactions? is it the intermediary, Intuit, that is having issues grabbing the available transactions or issues sending them downstream to Quicken? Is it your Quicken file?
it's really hard to determine 'root cause' and the biggest issue Quicken has is millions of laptops / desktops with a large variation of manufacturers, generations, software, etc.
Best to call Quicken Support.
I have no explanation of why you experienced the issues that you did, but depending on how many transactions you are missing, it will probably be quicker to manually enter them versus spending an hour or more trying to get the missing ones to be downloaded.
I find EWC/EWC+ downloads problematic and unreliable, so I download a .CSV file from Discover and use ImportQIF (free from QuicknPerlWiz) to convert it to a QIF file for import into Quicken.
Note: There are drawbacks as stated here copied from the ImportQIF website:
But using the QFX format will allow for matching of transactions and using Quicken's system for filling in the categories even in the latest versions of Quicken which have dropped these features for QIF file imports.