The PHP Max Input Vars is the maximum number of variables your server can use for a single function to avoid overloads. The default value of max_input_vars is 1000 but you can change this in the Platform.  Increasing max_input_vars may helps in resolving issues with your menus. If they're not saving or being truncated, then increasing this value may resolve the issue.

Log in to the Platform and select the website from the dashboard, and then select Upgrade PHP Version or PHP & Databases from the side menu.

Scroll down to the PHP Configuration section and click Add Variable.  Type max_input_vars in the first box and enter the value in the Value box, our suggestions will populate when you click in the Value box.  Click Update Configuration to save the changes.