As discussed in PR #3341 there is some issues with exporting projects containing a Sample Track. I've only seen this when using SDL. ALSA works fine and other sound engines I haven't tried.

The renderer process will simply hang and never return to main(). If you do a --rendertracks export it will stop on the first Sample Track it tries tor render.

I'm not done bisecting this but it may have happened around these commits 8497d39 e55ec80