If you’re trying to use Ajax login on Listeo and you get stuck on message ‘Sending user info, please wait…‘, first check if you have any cache/optimizations plugins active on your site. If you do, try to disable them to see if that help. If it does, you might need to change some settings in those plugins as they might have to aggressive optimization for this feature to work.
The issue is often connected with custom mod_security rules. Some hosting providers block login requests from non standard paths, so try to contact your hosting provider and ask them about it.
And last but not least, you may experience this issue on nginx server, in that case, add the following lines to /etc/nginx/nginx.conf
fastcgi_buffers 16 512k;