Select all in Observables tabs's report is not working well

[jpkha]

Go to a report details, observable tab add new entities, and check the list.

If you add entities on an empty list at the beginning, the bottom bar is not visible.

If you add entities on 2 entities in the list at the beginning, the bottom bar is visible but shows the wrong number element.

The background task is okay, we are sending the correct filter.
Do not launch the background task until this PR is merged : #6195