I believe the issue I am seeing is related to this
[Tasks stuck with "waiting for Pulp to start the task" - foreman-2.4 / Katello 4.0.0 / Pulp3]
with a slight variation.
I see the repo sync jobs waiting for days and never finishing but on my system doing curl https://puppet.ensco.win/pulp/api/v3/status never returns a response.