Is there a Clojure project or code example / setup that I can try reproduce the issue? What OS is this on? I seem to recall different audio setups between Linux, Macos, etc It's been a decade since I did overtone, the main problems I had were with the audio interface on the operating system locking up randomly

This is literally all you need to do in order to reproduce this. I'm on Linux right now, I'd test on other OSes if I could.

(ns test-project.core
  (:use [overtone.live]))

(ns-publics 'overtone.live)

So can overtone work without running a jack Daemon now? If not, what is the setup used?

Have you tried to require overtone with an alias instead of use?

I don't understand the last part of the question where you say the issue is not there when running LSP or Cider?

When `(:use [overtone.live]) is evaluated it will try start a local supercollider and try to connect to the jackd daemon (through alsa or pulseaudio, which ever has been set up - assume pulseaudio is needed on the last few years of Ubuntu Linux - that seems quite a fiddly setup) If the connection to jackd fails, then the REPL process will most likely terminate (mine does). Overtone is also quite sensitive to JVM options and wouldnt be surprised if there are issues if running a JVM other than from Java 8. I am not able to get the server to run when using through the command line, so have no way at the moment to replicate this issue. I would recommend uising https://ubuntustudio.org/ rather than Ubuntu to develop with Overtone, as it comes configured with jack.