Create a php file called phpinfo.php or whatever you want really. Put this in it:
Upload the file to your server and open it in a browser. Look for post_max_size in the page that's displayed.
Or, if you have access to the php.ini file you can look for post_max_size there and see what it's set to.
This information will tell us whether your server is setup to accept uploads larger than two megabytes. If it is then there could be a bug somewhere in PP, but without this information, or other confirmed cases of the same problem, it doesn't make sense to start digging through code for a solution that's completely separate from the application.