Need help! Encoder will not queue my file

I'm still fairly new to Adobe. I need to use Premiere for work. I'm trying to export a 2.5 minute GoPro video into media encoder. I have it selected as H.264 match source- high bitrate. It opens media encoder 2020 and the file shows up from premiere. When I press the play button to encode nothing happens. I have uninstalled and reinstalled the program. I'm not great with the technical aspects of these programs. Any ideas how I can fix this? 
thanks!