sitemap missing “parent” pages in urls

I’m having an issue with the plugin when it “auto-generates” the sitemap on publishing a post. For many of my pages, which have parent pages, it misses some part of the complete url. e.g.
https://tech.shantanugoel.com/projects/misc-stuff
becomes
https://tech.shantanugoel.com//misc-stuff
and
https://tech.shantanugoel.com/projects/windows-mobile/shantztodaychanger
becomes
https://tech.shantanugoel.com/projects//shantztodaychanger
which causes google to generate a lot of 404’s.
However, if I manually rebuild the sitemap, it builds correctly. Anyone else faced this issue?