T-Mobile Speedtest app error

Hey everyone, I recently purchased a T-Mobile SIM along with their $30 plan to give it a try and have encountered an issue when I try to use the Speedtest app by Ookla. It gets through the download portion just fine, but half way through the upload portion of the test I get a "Network Communication Error". Have any of you experienced this? Is it an APN setting? My default service is the $45 Straight Talk plan, and I had to create an APN for Speedtest to work. I am using a stock Nexus 4 with the default T-Mobile APN. Any help would be appreciated!