Elliot,
This is overdue but I found an issue to this problem.
It comes from the max_input_var located in the php.ini file.
I’m using PHP v 5.4.4 which required adding the following line to the php.ini file to support saving fields that exceed the default limit. I’m not sure what the default is but here’s what I’m using now.
max_input_var = 100000
Source: http://stackoverflow.com/questions/10303714/php-max-input-vars
