I've just updated to the latest version (1.1.6.0) via ckan, and my KER window has disappeared from VAB (the main window showing all the buttons & delta-v).

Additionally, the "vessel" details got borked up, too.

I've reverted back to v1.1.5.7 and all is dandy.
Using ksp v1.6.1

1.1.6.0 was built against ksp 1.7.0, I didnt test it on 1.6.1, No idea why it would break. Will test now.

I have duplicated the problem and still have no idea what is wrong. Updating the CKAN version to min 1.7.0 for now.

Yeah, works perfectly well for me, too, once the ksp version is updated to 1.7.
That's the workaround :)