Genesyscloud_script dynamic prompt injection fails with 400

Need some help troubleshooting dynamic prompt injection in agent scripts.

Context:
Provider v1.22.0 on AU-1 BYOC. Attempting to inject runtime variables into genesyscloud_script prompt_text via Terraform. Hardcoded strings apply successfully. However, referencing local.var.customer_name triggers a 400 Bad Request during terraform apply. API logs indicate invalid prompt structure. The HCL block defines the prompt with variable substitution syntax supported by the provider docs, but the backend rejects it. No specific error message returned in the CLI output, only the generic 400 status. Has anyone successfully deployed dynamic prompts in this environment?