I solved the “Please wait” hanging issue by adding ‘www’ to the form URL on the form html code.
I set the action parameter (action="https://MYSITE.com/m…) to action="https://www.MYSITE.com/m
I changed this code:
<form autocomplete="false" role="form" method="post" action="https://MYSITE.com/m/form/submit?formId=25" id="mauticform_mmfthinklikeamfguru" data-mautic-form="mmfthinklikeamfguru" enctype="multipart/form-data">
by this one:
<form autocomplete="false" role="form" method="post" action="https://www.MYSITE.com/m/form/submit?formId=25" id="mauticform_mmfthinklikeamfguru" data-mautic-form="mmfthinklikeamfguru" enctype="multipart/form-data">