Null object reference on removing registry value

Using wyBuild 2.6.18.4.

I'm trying to do a simple remove value on a registry entry, but on update it fails and rolls back and then give the message "Object reference not set to an instance of an object.".

The update window always closes before I can click the show details button, so I'm not sure if that contains any extra information, and if it does, where that error log actually is.

Upon searching this error the only similar one I could find was another post about the same error when checking "only use 32-bit apps", but I'm not checking that, and apparently that was fixed anyway.

ThanksGary