A Google News Help thread has some reports of publishers reporting that their Google News Sitemaps are reporting “0 Indexed URLs” in Google Webmaster Tools.

I too saw this issue and I thought that perhaps there was a bug in my sitemap file. But Google did not report any issues with my sitemap file, plus, I saw my articles were being indexed within Google News. So I figured, it was a reporting glitch in Google Webmaster Tools. It appears I was right.

Inbal from the Google News team said in a Google News Help thread:

I assume this error is being fixed, but there is currently no estimate time for the fix.

Forum discussion at Google News Help.