Since both accounts are connected to QuickBooks Online, the easiest way to add the transaction is to Transfer from one of the accounts and then Match the transaction from the other account. Here are articles that’ll help you out:
Resolution for 'business CC issue: 'Posting Payments to Business CC' available: Yes.
The business CC 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 business CC issue yourself by looking for a resolution described in the article. If it is a complex business CC issue or you are unable to solve the issue, you may contact us by clicking here or by using other business CC support options.
For more information about resolving issues related to business CC in Quickbooks/QBO or to get support for the issue 'Posting Payments to Business CC', click the link below: