When a shulker box is placed using a dispenser, it doesn't cause a block update (comparator doesn't update output unless the inventory contents change or the comparator is updated).
When a shulker box is placed using a dispenser, it doesn't cause a block update (comparator doesn't update output unless the inventory contents change or the comparator is updated).
Please do not mark unreleased versions as affected.
You don't have access to them yet.