It usually happens on newer PHP versions (> 5.3.9) when max_input_vars value is not sufficient to transfer all the UberGrid settings. There is a number of ways to fix this:
1. On most of shared hostings: edit or create php.ini file at your WordPress installation’s wp-admin folder.
2. If you are running on VDS, you’ll need to add
max_input_vars = 10000;
to your main php.ini file (its location depends on a specific configuration).
3. Sometimes php.ini files are not processed. In this case, open your .htaccess file located at the WordPress root and add the next:
php_value max_input_vars 10000
It will allow 10x more cells than default settings.