[PD] Pd sometimes not outputting sound when launched on boot

[Alexandros]

I have an Odroid-XU4 running Ubuntu 16.04.3 LTS and I'm running
Pd-0.48-1 on it. I want to enclose it and use it headless so I'm
launching Pd on boot via crontab. This is what I've written in crontab:

@reboot sleep 30 ; pd -alsa -audiodev 3 -inchannels 2 -outchannels 4
-nogui -open
/home/odroid/Documents/Pd/3dPd/Pd_patches/modular_synthesizer.pd &

Half of the times I'm booting up the Odroid, Pd won't make any sound. I
have an LED controlled by a Teensy, which gets input from Pd when the
DSP goes on (through [r pd] -> [route dsp]), and it indicates that the
DSP is indeed on.

Is there some known issue, or anyone has something in mind?