Actually you have found the solution. startThread(4) does not look good. You should call startThread() or something like startThread(juce::Thread::Priority::low).
I didn’t write this, I believe it was auto generated, or possibly done by a friend that helped me. If I change like you suggest, will it work as well on PC?
I just used your first suggestion: “startThread()”. I have registered and activated the plugin after that and that worked. Haven’t tested the functionality though.