Page builder does not save items / not able to choose buttons

Hello,
i’ve 2 problems with the page builder plugin.

1. page builder doesn’t save my work, for example when I create a headline and save it, it’s gone.

2. I cannot choose buttons or menus. As the screenshot shows, it’s not possible to add a new feature. It’s the same with the other plugins.

First I thougt, the problem would be my browser. But I tried it with firefox, chrome and safari on different computers (win8 / mac) and the problem is still there. I installed the latest update, too.

So is there a solution for my problem?

Thanks for your help!