Visual Composer Bug in backend – Editor mode dont load.

Hello,
i am using your theme for two websites. For backend administration i installed Visual Composer Version 4.8.1.
If i try to edit the content of a page the VC doesnt load any more. There is only the loading wheel and after it there is no element. But there are still some existing elements in the code, when i switch to normal mode.
I can only edit the pages in classic mode what is not really comfortable.

See the screenshots:
http://www.pixhoster.info/f/2016-08/08d14998404a85f2229fdfde8f71eae3.png
http://www.pixhoster.info/f/2016-08/9e2c20ff162f2dcfb9cd9e9329ff1628.png

I am using the Google Chrome on Mac. Both with actual versions. Also in Mozilla Firefox the VC doent load. WordPress is running under 4.5.3.
Is there any product licence code, which i need to update it?

I am looking forward for your feedback.
Kind regards
Andy

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