Solution
A data fix can be applied to amend older versions of the form.
Type talk to a person and the Digital Assistant will put you through to a live support agent.
When accessing a form, you may see the error message:
The _____ page is not available for the person role selected.
This prevents the form from being accessed.
Why this happens
The error typically occurs for specific historic versions of the form, not all versions.
Older versions may have mismatched names in their XML compared to the latest version, often due to differences in capitalisation.