I'm one of the many folks who has been experiencing the CC-800 issues.
After following a support tech's advice to "copy" my data file and then re-authenticate all of my accounts, I am now being presented with a 2FA authentication prompt (SMS to my mobile phone) for my Venmo account every time I do an OSU.
How can this be fixed? This wasn't a problem until I followed the steps that I was given by Quicken Support.