Bulk Update BLOCKS lacks ability to select Issue Number

[scott_lake]

Scenario:  multiple issues need to all be assigned to a specific work package issue. Assignment to work package involves making the issues 'block' the specific work package.  

Error:  Bulk change of the multiple issues allows 'BLOCKS' field type to be selected, but there is no possible way to actually assign which issue to block.  The Bulk change tool randomly selects an issue number (or no issue at all)

[Nic Brough -Adaptavist-]

What type of field is "blocks"?