play command not working in mint 18

[rynnon]

same issue as bengm, but in a different environment so his fix doesnt work for me. the relevent problem description, as copied from his post:

I cannot get the play command (ctrl-r) to work. Troubleshooting steps:

• sonic pi is running and cli is installed.
• sonic-pi-cli seems to be working fine. sonic_pi play 70 or sonic_pi run_command 'play 70' both work fine from the command line.
• If I manually start a script in sonic pi, then go over to atom and run the ctrl-s command, it successfully stops playback.
• If I have a simple file (i.e. containing only play 70) and run the ctrl-r command, I get the success message within atom "Sent source code to Sonic Pi"; however, the sound does not play

my environment: linux mint 18 sonic pi v2.9 atom 1.10.2