sitemap status are all pending

I have 5 domains currently active on a single Drupal base each domain with about 1000+ nodes assigned by domain dedicated content types.
Since the simple xml sitemap only creates 8 node links, I thought this module can solve the issue.
Seems like the sitemaps are auto generated for all active domains, but all are in pending status in Sitemaps -> status.

wonder why all sitemaps are in pending status.