Thank you for taking the time to visit the Community and adding to this discussion, though I apologize for the trouble.
When I looked into the error that you are all receiving, it refers to the financial institution as having an unsupported MFA protocol. Here is a link to a Knowledge Base article that explains it more.
Also, when I try connecting to LPL in my own Quicken, I get the following message; "CC-592 Quicken cannot connect to your accounts as they are set up at LPL Financial. You need to contact LPL Financial to correct this issue. (Tell them you received message CC-592.)"
So this financial institution is on the list in your software because it is supported by both Quicken and LPL. It seems to me that somewhere along the line changes took place that have, in turn, caused the issue. The article I linked above does give a few suggestions of things you can try to resolve this. Unfortunately, if those suggestions do not work, you will need to contact LPL for further assistance.
Do let us know if you have any more questions or concerns and we will be happy to answer those the best we can.
Quicken Alyssa