I'm going to summarize my comments to both of yours here since they overlap a lot.@robdille
On the "didn't work". I see that you didn't select the "fix". I just want to note that I tried that recently and it actually did seem to fix the problem without any loss of data for the account. But note since reset cloud data wipes all the data at once I think it is a better fix when multiple accounts are involved.
As far as what you can do to prevent it from happening again. Well since we really don't know what caused the problem in the first place no one can tell you that. One guess might be that the switch from the old FDS system to the new QCS system caused the problem, and once fixed might not happen again.
On Chase accounts. Direct Connect is free on Chase non business accounts. There isn't a special username/password for it, but you do have to enable it at the Chase website.
Select the person icon in the upper right then Profile & settings -> AccountSafe/Manage access -> Desktop software/see more
On that page it should allow you to enable it.@ronaldmcohen
I don't think robdille knows how to switch from QCS to FDS, that information that you posted was edited out by the moderators (Quicken development doesn't want people switching)
On you having some Chase accounts setup for Direct Connect and some for Express Web Connect and the "ain't broke" statement. I have never believed in that statement. It is used most of the time to neglect proper maintenance. In my work I have to deal with very old code that could have been maintained quite easily if they keep up with it, but they wait until it breaks and then can't understand why it is much harder to change 20 year old code so it works again.
Direct Connect has always been the better system. It has "fewer parts"
Quicken -> financial institution (OFX server dedicated to this purpose)
Standardized protocol (OFX standard)
Express Web Connect has always been a problem system that will continue to be a problem.
Quicken -> QCS -> Intuit server -> non standard website
Ad hock system which is an "agreement" between Intuit and each financial institution (not necessarily the same agreement) on how to log in, and how to fetch the data, and what format it is in (Intuit does a conversion for most of these).
Note that there is also Web Connect. Which is downloading the QFX file and importing it manually. Clearly if one goes with this over either Express Web Connect or Direct Connect that is just a personal choice on convenience. Nothing wrong with that from a maintenance standpoint. BTW a QFX file is simply the "response" that would have been sent if Direct Connect was used. As in Direct Connect sends a "request" and the OFX server sends the "response". If you look at the OFX log you will see this interaction.