ALT+ DEL (clear target segment) grayed out in Trados Studio 2015 SR2

Since updating to 2015 SR2 I can no longer clear target segments. ALT+DEL does not work and the option in the ribbon and under the right mouse button are grayed out. The segment status of the segments I wish to clear is "untranslated". Has anyone else experienced this and/or does anyone have a solution to this problem?