TLS Inspection not working on all pages?

[PotatoCarl]

Hi
I tried to install the webproxy with TLS inspection and ICAP. However, this does not work on all pages.

While https://www.spiegel.de loads fine, https://faz.net is not loading at all (access denied by proxy). Many other pages, e.g. this forum work.

I cannot find the reason for that acutally. Even if I specifically insert an exception in the SSL inspection, or in the access lists, it still does not load faz.net.

Is there any way to find out what is actually blocking the page?

BTW: Funny enough, the EICAR test file is loaded both with https and with http....