I suggest checking the log files of what is being downloaded from the financial institution.
If the download method is Direct Connect or Web Connect .QFX file download, the log file to look in the is OFX log. Express Web Connect and Express Web Connect+ methods use the Quicken Cloud Services log.
You will find the log files by going to Help→Contact Support→Log Files.
For the OFX log, save it to a .txt file and view it using Notepad. The Quicken Cloud Services log can be viewed directly.
Report back with your findings of whether or not the transactions are shown in the log.
Yes, the log files are confusing gibberish, but the thing to do is search for the amount of the transaction in question. Once found, look around near it for a date to make sure it is the correct one if the transaction is a recurring one of the same amount.
The idea is just to find out if it is in the download, nothing more than that.
As to the errors, I have no information.
In those searches, did you use any characters such as $ or a comma? Don't. Numbers and the period only.
If you haven't done so already, I'd say it's time to call Quicken Support on the phone during posted hours of operation and request help. Let them do a screen share session with you to review the situation on your computer, to determine the nature of the problem and to figure out how to fix it. The errors you mentioned, FDP 103, might well be the cause.
Quicken Support: