Add to Document Builder button grey out

Summary:

We were able to create PO previously. However just recently, we are not able to because the Add to Document button is not enabled when we choose a PR line to process.

Is there a possible reason for this?

How to solve this issue?

Thank you in advance.

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

23D

Code Snippet (add any code snippets that support your topic, if applicable):