"updated_at" hash key remains after removing jobs

Hi,

I use Kue with two workers running on two different (Heroku) machines.

I am testing with a batch of 25000 jobs that are consumed by the two workers and what I see when they are done (I confirm the 25000 jobs executed properly) is 1000+ of leftover jobs (i.e. named `q:job:number`) with only a `updated_at` field.

As a side note, I only see this behavior with two workers. With one worker they are no leftover jobs.

Do you have any idea on how this could happen and how to fix it?

Thanks a lot!