Sfizz Crashes with puredata when changing dsp status in external patch, assert faied !voice->isInSisterRing

[mward25]

SFizz crashes puredata when you perform the following action with this This minimal reproduction:
sfizz_reproduce.pd.gz
Steps:

1. Open the patch "pd testSubPatch" move the window somewhere else, then click into the main window.
2. Ensure Dsp is on (ctrl-/)
3. Hit the toggle switch above the "metro" object
4. Click into the other window
5. Turn Dsp off (ctrl-.)
6. Wait up to 30 seconds (rough estimate).

Output from Puredata:

Assert failed: !voice->isInSisterRing()
Assert failed at /usr/src/debug/sfizz/sfizz-1.2.1/src/sfizz/SisterVoiceRing.h:139
Trace/breakpoint trap (core dumped)

EDIT: Figured I should mention this patch I'm working on also crashes, but it does so faster, and with less work (just open it, and click the toggle above the tempo object). It requires the live coding toolkit (https://github.com/algomusic/Live-Coding-Toolkit-for-Pure-Data). It normally crashes after the clarinet starts. Here's the patch:
try_canvas.pd.gz