Most Tax Hub readiness problems are caused by incomplete business configuration rather than the reporting workspace itself.
When a registered address exists, Tax Hub uses it for statutory identity. Otherwise, it uses the default trading address. Correct the underlying business address rather than editing a prepared payload.
Synthetic datasets are useful for demonstrations and publishable screenshots. They are not part of normal business initialization and their conspicuous test identifiers must never be copied into a live reporting profile. See Synthetic Datasets.
Check the accounting period, Cash Code classifications, opening balances, adjustments and underlying transactions. Rebuild affected periods where appropriate, then reopen Tax Hub and review the Payload Audit or Accounts Validation result.