Using :until_and_while_executing not yielding expected results

[gdgp]

Using sidekiq-unique-jobs 4.0.18, redis 3.2.4, sidekiq 4.2.10, rails 4.2.7.1, ruby 2.3.7.

According to my understanding (reinforced in previous issue), when using the sidekiq_options unique: :until_and_while_executing I should be able to enqueue Job A with arg X, then if while it is enqueued I try to enqueue another Job A with arg X, it does not allow it, but then, once the job starts being processed (leaves the queue), once I try to enqueue another Job A with arg X it should get enqueued, but not processed because there is still another one being processed.

The part that is failing is enqueuing Job A with arg X when the first that was on the queue left it and is being processed. It only lets me enqueue another one once it finishes processing the first one.

What might I be missing?

Thanks in advance