Admin options not being saved

Hi!
I’ve got a problem when trying to save the options. The save option it’s not working, the checkboxes appear checked again and again.

Also, some errors are appearing in my log:

Undefined index: label in /var/www/vhosts/myserver/domain.com/wp-content/plugins/woocommerce-custom-options-lite/custom_options_html.php on line 41
[14-Dec-2016 11:42:38 UTC] PHP Notice:  Undefined index: price in /var/www/vhosts/myserver/domain.com/wp-content/plugins/woocommerce-custom-options-lite/custom_options_html.php on line 42
[14-Dec-2016 11:42:38 UTC] PHP Notice:  Undefined index: max in /var/www/vhosts/myserver/domain.com/wp-content/plugins/woocommerce-custom-options-lite/custom_options_html.php on line 43
[14-Dec-2016 11:47:39 UTC] PHP Notice:  Undefined variable: data_msg in /var/www/vhosts/myserver/domain.com/wp-content/plugins/woocommerce-custom-options-lite/classes/class-product-add-to-cart.php on line 6

Any help would be appreciated!
Thanks!