It’s completely fine. I probably just explained it a bit poorly.
It is indeed in the Appearance –> Menus admin page.
But it would seem that it is the default wordpress limits the memory for a menu
It seems to be solved by changing max_input_vars in the php ini file
max_input_vars 1000 PHP_INI_PERDIR Available since PHP 5.3.9.
It’s not CMW related at all I found, and I’m sorry if you used time trying to figure this out
