Add custom fields not run

Have you tried refreshing the browser on that page?

Yep the problem is that when you drop the new element it always returns at the original place at bottom of the page where you has create it , not run incrustate it between the other standat fields it always returns

This occurs always, the custom field is never linked in the screen ,always returns how when you drag a field in a wrong site

Can you post your screenshots on the plugins forum?
at here