This happens when you access Confluence using a URL other than the BaseUrl or Confluence. Please make sure you are accessing Confluence using the BaseUrl set in the system.

Baselines for Confluence does not keep a copy of your documents (pages or attachments) but rather keeps links to those documents. If you delete those documents from Confluence, their links will remain in previously created baselines but they naturally will not be reachable from Baselines.

Baselines for Confluence utilizes the export library of Confluence. This library may have issues exporting large number of pages at once. The exact number depends on your server capacity and memory settings but is usually over several thousand issues.

As a workaround you can create additional baselines (that have the same Baseline Date as your original baseline) that include a subset of pages and export them individually.