Although that obviously not the case for you...

I just did a quick google and the Instructure wikirecommends that you check the last error that Canvas had (if any) after some scheduled job (such as email) by running:

psql canvas_queue_production -c "select last_error from delayed_jobs order by updated_at desc limit 1;"

Does that give you any hints?

Thanks very much for reporting Teddy. We can confirm that this is a bug in the Canvas appliance. I have lodged it as a bug on our issue tracker.

We are currently working on a fix and will provide a workaround ASAP.

I have discovered that the issue is because the Canvas "delayed job" backend is not running; hence why there also are no errors. I have worked out how to fix it but need to do a little more testing to refine the exact minimal fix. I will post back ASAP.

Here's the workaround.

You'll need to login as root and copy/paste the following:

adduser --disabled-password --no-create-home --gecos "Canvas user" canvasuser
adduser canvasuser www-data
echo "PassengerDefaultUser canvasuser" >> /etc/apache2/sites-available/canvas.conf

WEBROOT=/var/www/canvas
USER=canvasuser:www-data
chown $USER $WEBROOT/config/*.yml
chown $USER $WEBROOT/config/environment.rb
chown -R $USER $WEBROOT/log
chown -R $USER $WEBROOT/tmp
chown -R $USER $WEBROOT/public

service apache2 restart
service canvas_init start

Then it should all work as it's meant to...