@idalhaug are you seeing any error? You can turn on debugging following the steps here.
There is a predefined limit however it is not determined by the number of records POSTed but rather the POST size. Look at your php.ini file (line #656 depending on your installation method, I'm referencing Bitnami) for the following:
; Maximum size of POST data that PHP will accept.
; Its value may be 0 to disable the limit. It is ignored if POST data reading
; is disabled through enable_post_data_reading.
; http://php.net/post-max-size
post_max_size = 40M
You can change the 'post_max_size' directive to a larger value to see if this resolves the issue you are facing.