Random Playback Failure?

I’m using an Asus laptop with Windows 10. I’m very new to Sonic Pi and to coding in general, but I’m slowly building my first composition. I am up to 200+ lines of code including rings, threads, iterations. Usually playback works fine, but randomly I get nothing from the one buffer with the my main composition but other buffers with smaller chunks I’m working on will play. I’m not getting error messages. If I close and reopen the program it’ll play again. Is it just an issue with the length of the composition?

It could be. There is a maximum size of coed that a buffer can work with. You can get around it for large files by using the run_file command. Syntax is:
run_file "path/to/your/filename"
You can then run very long files.
See this previous post.