How do we pass the employee’s e‑signature captured in the UI into the BI Publisher template?

We have a Journey task that includes an E‑Signature activity. The employee signs directly in the self‑service UI, and the signature image is saved in the task details screen. However, when we generate the final document through our BI Publisher template (which is registered on the task’s “Document Records” definition), the signature is not appearing.

Could you advise on the correct end‑to‑end setup so that the captured signature becomes available in the template?