postmeta > url field for Custom Link deleted when saving menu

Hi,

I have come across this issue when saving menus – the ‘_menu_item_url’ field is saving correctly, but the ‘url’ field is deleted whenever the menu is saved.
This is the field that’s used to create the link on the front-end.

This is happening for all Custom Link menu items. Everything else is fine.

I have tried deactivating all plugins, and I have also increased these variables in php.ini, which was the closest thing to a solution I could find online:
max_input_vars = 9000;
max_input_nesting_level = 500;

It was fine before the site was updated to WP 4.3.

Any suggestions for a fix would be much appreciated – I have put the values directly into phpmyadmin just to get it working for now, but that’s not ideal.

Thank you!