I was just trying to submit about 10 x 15 records... and found that cakephp was failing with a validation error. Found out it was due to the following in the php error log.

[09-Jun-2016 19:16:22 Australia/Melbourne] PHP Warning:  Unknown: Input variables exceeded 1000. To increase the limit change max_input_vars in php.ini. in Unknown on line 0

Open php.ini and edited from 1000 to 2000 and then restart (in my case) php-fpm

; How many GET/POST/COOKIE input variables may be accepted
max_input_vars = 2000