Recurring CC-800 error with updating Discover account

This issue has been occurring for weeks when trying perform a one-step update. I have tried deactivating and reactivating the account many times. Each time the account reactivates successfully and downloads transcations. However, at the very first update after that, the dreaded CC-800 error returns. I've also tried a “validate and repair” on the data file. I have contacted Quicken support on this issue twice and received three suggestions. One was to “Exit Quicken, wait 4 hours, and try again”. The second was to create a new Quicken data file and start from scratch…sacrificing all historical data for ALL ACCOUNTS in the process. And the third, was to restore from a weeks-old backup and start from there again - sacrificing weeks of data from the entire Quicken data file in the process.
Surely, there must be a better option…