I just did the same instructions 15 days ago.
cd /var/discourse
./launcher enter app
"/shared/letsencrypt"/acme.sh --cron --home "/shared/letsencrypt" --force
exit
The first thing I learned was that if you view the certificate with Chrome it may show invalid when in fact it is valid. See: Chrome / Chromium bug: SSL certificates show incorrect (expired) dates
I then tried
me@site:/var/discourse$ sudo ./launcher rebuild app
which did not work and finally
sudo reboot
The site was then working as expected.
While I note the step about rebuild I am not sure if it is needed, but it was a step I did along the way.