Aria2c will not exit after sucessful download

I am using the below aria2c command to call an API that downloads a file to a directory. Though the process completes and I get "download complete"... aria2c does not exit to the command line, I have to hit enter to get the command line. I am not sure what is wrong. Am I missing something in the manual? Thank you :).

aria2c -x 4 -c -d  /home/cmccabe/s5_files/plan --seed-time=0 --use-head=true --http-user  "<user>" --http-passwd <password>  http://xxx.xx.xxx.xxx/yy/yyy/yyyyy/?format=json