Declarative Agent with SharePoint Capability Returns "Sorry, I wasn't able to respond"

Questions:

1. Does SharePoint grounding require a Microsoft 365 Copilot license?
2. Can CDX accounts test declarative agents with SharePoint access?
3. Do I need a Microsoft 365 Copilot Developer license specifically?

Setup:

• Declarative agent with items_by_url pointing to SharePoint site
• CDX test account (no Copilot license)
• Provisioning succeeds, but agent doesn't respond
• Regular M365 Copilot (web search) works fine
  Is the license the blocker, or could there be another configuration issue?

Thanks!