I have answered to this question in the opened support ticket on the same topic. Please let us continue the conversation from the there, so that I could be able to track the provided information more properly.
For anyone interested in this matter:
This problem is generally reproduced when the httpHandlers are missing form the web.config file of the application. More about this, you can find in this article
Additionally, related behavior could occur due to a browser limitation in IE
and because of it some of the CSS rules are not loaded into the content of the page. If this is the case, it is recommended to enable the CDN support
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