Blank page after V3 update

I have a really serious problem with the latest update  of the Oblivion theme.

All pages and posts are blank after creation or editing.

One thing I noticed  was this:

That upper line should not be there right?

And if I select any other sidebar I get a working page that doesn’t have a side bare and everything is swapt around.

So any help would be more than welcome!!

O, and I have turned of all plugins to test if that could be it, but didn’t fix the problem.