CTRL+Backspace not working on e2studio 7.3.0

I have tried editing the Keys settings, (see screenshot) including adding new bindings and changing the "When" properties.

The other bindings have not worked so far; shift+backspace deletes one character, alt+backspace has no noticeable effect. 

CTRL+Backspace everywhere else in e2studio (including the filter text box where the text "delete previous" appears in the screenshot), as well as other programs -- it is only in editing the source file itself that the functionality doesn't work. 

(Edit: CTRL+left/right arrow also don't work, and neither does CTRL+Space for the Content Assist; however CTRL+C/V for copy/paste does work, as does CTRL+I for formatting. CTRL+C/V/I are set to 'In Dialogs and Windows' for the When property, but changing the CTRL+backspace/left/right to that same When does not succeed)

Anyone else having a similar problem, maybe a workaround they've found?