TrendMD Plugin - Unable to save code snippet

I am using OJS 3.0.2 for our journal hosting (http://amphysiol.com) with defaultManuscript theme.
Recently I have installed trendMD (https://www.trendmd.com/) plugin for OJS 3.x. After enabling the plugin, I am not able to save the code snippet in setting. Web browser console is showing the following error

Failed to load resource: http://amphysiol.com/index.php/amp/$$$call$$$/grid/settings/plugins/settings-plugin-grid/manage?category=generic&plugin=trendmdplugin&verb=settings&save=1 the server responded with a status of 403 (Forbidden)

A screen cast of the process is available at google drive.

Any help in this regard.

Issue resolved. The problem was with Mod_Security of the hosting server. After disabling the Mod_Security, code snippet was saved successfully.