On my box, I see the upgrade for the Web If and it appears to install but when checking the version number in Settings it is set to 2.76. Is there a way to force upgrade to the latest version? Perhaps via telnet session.
The web-if upgrade remains in the upgrades available page.
Probably the easiest way for you to sort things out is to do a complete reset of the CFW environment.
Open a telnet session to your HDR and enter this command rm /opt/etc/.DO_NOT_DELETE_THIS_FILE then restart the box. (make sure to include the "." at the start of the file name). This will reset everything back to the point where you first flashed the custom firmware with no packages installed. You can then do a clean re-install of the full web interface and apps once again, via the basic web interface.