I have had this issue with Citibank. Waiting works. It is caused by the bank feeding into qbo. Here is how you can try disconnecting and reconnecting. That sometimes works: http://www.artesanibookkeeping.com/disconnect-bank-feed/

Resolution for '334 error issue: 'Bank balance not updated in 7 days. System won’t allow a manual update: 334 error. No change in customer ID/pin/password in this time frame, worked fine before. Help?' available: Yes.

The 334 error issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the 334 error issue yourself by looking for a resolution described in the article. If it is a complex 334 error issue or you are unable to solve the issue, you may contact us by clicking here or by using other 334 error support options.

For more information about resolving issues related to 334 error in Quickbooks/QBO or to get support for the issue 'Bank balance not updated in 7 days. System won’t allow a manual update: 334 error. No change in customer ID/pin/password in this time frame, worked fine before. Help?', click the link below: