Same Problem here aswell, unfortunately theres not really an alternative to this plugin (well not that I know if) otherewise I wouldnt rebuild the menu monthly ??
Seems to be an ajax problem by me, everytime it trys to sync theres an Console error:
jquery.min.js?ver=3.6.0:2 POST wp-admin/admin-ajax.php 500 (Internal Server Error)
send @ jquery.min.js?ver=3.6.0:2
ajax @ jquery.min.js?ver=3.6.0:2
s.ajax.s.ajax @ jquery-migrate.min.js?ver=3.3.2:2
n.syncNesting @ nestedpages.min.js?ver=3.2.0:formatted:673
t.syncOrder @ nestedpages.min.js?ver=3.2.0:formatted:2171
(anonymous) @ nestedpages.min.js?ver=3.2.0:formatted:2146
dispatch @ jquery.min.js?ver=3.6.0:2
v.handle @ jquery.min.js?ver=3.6.0:2
