Did you use the 1099 wizard and click the Select None (or similar) option?  This actually writes back to the vendor records. I’ve no idea why Intuit did such a thing…

Resolution for '1099 Vendors deselected issue: 'Why were 1099 Vendors deselected?' available: Yes.

The 1099 Vendors deselected 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 1099 Vendors deselected issue yourself by looking for a resolution described in the article. If it is a complex 1099 Vendors deselected issue or you are unable to solve the issue, you may contact us by clicking here or by using other 1099 Vendors deselected support options.

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