All items should be selected, similar to the behavior on Admin / Products / Catalog. Instead, you have to perform one more click (click "Select All" in dropdown). The behavior should be consistent across all pages where there is a list of items with checkboxes.
Actual result
Dropdown menu opens instead, forcing you to do one more click, which is inconsistent with the behavior in Admin / Products / Catalog.
Preconditions
Steps to reproduce
Expected result
Actual result
Original Report: https://github.com/magento/magento2/issues/8986 by @thdoan