Stuck jobs in development mode are a known problem with Sidekiq and Rails 5.1
It’s probably because of missing dependencies. See the following post for more information on that.
Feel free to send a pull request if you find missing dependencies in sidekiq jobs.
Unfortunately the ProcessPost job can’t be fixed that way. We are aware of the problem…
As a workaround you can change config.eager_load to true in development.rb