… indeed, this is a bug! Goolge sitemap expects to get the English notation of a float. In line 26 of https://plugins.trac.wordpress.org/browser/bwp-google-xml-sitemaps/trunk/src/sitemap/sanitizer/xml/priority.php you should replace
return sprintf(‘%.1f’, $value);
by
return number_format($value, 1);
Thank you!
