When doing a Revise action, the "Parent Collector" is not affected by the filter, the Manufacturing View is displayed instead a Design View.
If the item is forbidden in the collecter, the user may be able to selecte it and delete it from the list.
The case that have been rised here is quite particlular because the parent item is at the same time in "where used" as Manufacturing at a first level and as Design in second level as you can see in the screen shot enclosed
When collecting the user was blocked because the collector has taken the first level (here in manufacturing view).
If he could remove this ban line to collect in two steps: first collection of the item design and then collect choising the parent item of this item in Design this time ( and not in manuf as in the first collection ), then he would be no longer bloked.