I continue to run into this issue. Sometimes it happens and if I change something in the code (minor, unrelated) or restart Matlab and it will output.
Other times, like RIGHT NOW (very frustrated) there appears to be nothing I can do to export this to PDF. I've had this issue on multiple versions :(.
I'd like to see MathWorks work on fixing this as they are clearly putting work into Livescripts and having the ability to run an analysis and export to PDF is super useful (still some formatting controls to work out, but I'm patient on that).
I'm running 2019b, on MacOS 10.14.6.