Wells Fargo account balance problems

For more than a week now, Quicken has been giving me an error message (cc-601) about not finding accounts with non-zero balances at Wells Fargo. At some point these Quicken/Wells Fargo issues also caused my Wells Fargo checking account balance to show in Quicken as 0. I'm not sure where or how the data in that account register changed to show a 0 balance. Has anyone experienced this same problem? Have you been able to diagnose more precisely how the data changed? Is there a fix?