Bug 19233 added the ability to push report results into item batch modification when the report includes a column of itemnumbers. However, only items on the first page of item results will be pushed to batch modification -- if the report results include 1200 items and the report page is set to display 1000 rows per page, only the first 1000 items will be batch modified. Koha is clear that it's only modifying those 1000 items, but it still creates extra work, especially since the Rows Per Page dropdown on report results doesn't include an option for All.