QUESTION strange behaviour since upgrade to 3.3.6

[df8oe]

Subdomain?
Proxy?

both NO.

Today I don't have time to take a look but I will do next possibility.

If error occurs I was not able to see editor on a Windows-machine using google chrome browser where I never have called the URL - so it is definitly not browser cache e.g.

I am very astonished but interested in debugging, too. For today evening I am glad that normal operation can go on

Best regards
Andreas