Dear Sir
Please add the domain, admin and ftp account in the 'Website Information (for Admin Only)' box to check directly
Thanks

I solved. The problem was in the italian translation "Toolbar".

I replaced

$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left" role="toolbar" aria-label="Toolbar">','<div id="editor-xtd-buttons" class="btn-toolbar pull-left" role="toolbar" aria-label="Toolbar">'. $button.'</div><div class="toggle-editor btn-toolbar pull-right clearfix">', $page);

with

$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left" role="toolbar" aria-label="Barra degli strumenti">','<div id="editor-xtd-buttons" class="btn-toolbar pull-left" role="toolbar" aria-label="Barra degli strumenti">'. $button.'</div><div class="toggle-editor btn-toolbar pull-right clearfix">', $page);

Dear advin

Thanks for your solution.
yes, you are right. it is various for the each language when you use to login admin

thanks

I have the same problem, i update the code and nothing.
Joomla 3.9.5 and shortcode 3.1 with spanish lang.

Dear siNNer

This issue relate to the language used when login admin and your editor.
The shortcode 3.1 for joomla 4.x, please install the version for joomla 3.x.
if you can't fix it please submit the ticket www.smartaddons.com/support/tickets and send us the information of your site to check directly

thanks