[Plugin: WP Realtime Sitemap] Default Options not updated

After setting the plugin options (e.g. Sort order descending) and updating by means of ‘Update Options’ button the database record shows correctly

a:11:{s:11:"sort_column";s:5:"title";s:10:"sort_order";s:4:"DESC";
s:10:"show_count";s:2:"no";s:9:"show_date";s:2:"no";s:10:"show_pages";
s:3:"yes";s:10:"show_posts";s:3:"yes";s:13:"show_archives";s:3:"yes";
s:15:"show_categories";s:3:"yes";s:17:"category_tagcloud";s:2:"no";
s:9:"show_tags";s:2:"no";s:13:"tags_tagcloud";s:2:"no";}

After leaving the WP Realtime Sitemap Settings screen and checking the database record, it shows the options are back to default:

a:11:{s:11:"sort_column";s:9:"post_date";s:10:"sort_order";s:3:"ASC";
s:10:"show_count";s:2:"no";s:9:"show_date";s:2:"no";s:10:"show_pages";
s:3:"yes";s:10:"show_posts";s:3:"yes";s:13:"show_archives";s:3:"yes";
s:15:"show_categories";s:3:"yes";s:17:"category_tagcloud";s:2:"no";
s:9:"show_tags";s:2:"no";s:13:"tags_tagcloud";s:2:"no";}

This means one can not change the plugin’s options.

https://www.ads-software.com/extend/plugins/wp-realtime-sitemap/