Crashes permalink structure

I appreciate if I can get help with this, thanks!

I’m not able to reproduce this behaviour. I use the %postname% permalinks as well, but without any problems.

can’t reproduce

I am also having permalink issues with this plugin. My permalink issues resolved when I deinstalled it.

in simple-multisite-sitemaps.php line 43 try

alter
add_action( 'init', 'jb_sms_sitemap_flush_rules' );

to
register_activation_hook( __FILE__, 'jb_sms_sitemap_flush_rules');