ATS blocks connection although requirements are met

Hi,

I am trying to send a POST request to pages.jumio.com where I am getting the following error in the debug console:

"App Transport Security has blocked a cleartext HTTP (http://) resource load since it is insecure. Temporary exceptions can be configured via your app's Info.plist file."

For a few months we're trying to get this server properly configured, and thought we succeeded already - but obviously we aren't and not able to find out what's wrong.

A quick check on SSL checker says everything is correct:

https://www.sslshopper.com/ssl-checker.html#hostname=https://pages.jumio.com/index.php/leadCapture/save

Even the "nscurl --ats-diagnostics" command tested all conditions with result "PASS" (see below).

Please let me know what's left to make this work.

best regards,

Philipp

nbmaclnzpr:BAMCheckoutDemo prakuschan$ nscurl --ats-diagnostics --verbose https://pages.jumio.com/index.php/leadCapture/save
Starting ATS Diagnostics


Configuring ATS Info.plist keys and displaying the result of HTTPS loads to https://pages.jumio.com/index.php/leadCapture/save.
A test will "PASS" if URLSession:task:didCompleteWithError: returns a nil error.
================================================================================


Default ATS Secure Connection
---
ATS Default Connection
ATS Dictionary:
{
}
Result : PASS
---


================================================================================


Allowing Arbitrary Loads


---
Allow All Loads
ATS Dictionary:
{
    NSAllowsArbitraryLoads = true;
}
Result : PASS
---


================================================================================


Configuring TLS exceptions for pages.jumio.com


---
TLSv1.2
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.2";
        };
    };
}
Result : PASS
---


---
TLSv1.1
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.1";
        };
    };
}
Result : PASS
---


---
TLSv1.0
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.0";
        };
    };
}
Result : PASS
---


================================================================================


Configuring PFS exceptions for pages.jumio.com


---
Disabling Perfect Forward Secrecy
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


================================================================================


Configuring PFS exceptions and allowing insecure HTTP for pages.jumio.com


---
Disabling Perfect Forward Secrecy and Allowing Insecure HTTP
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionAllowsInsecureHTTPLoads = true;
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


================================================================================


Configuring TLS exceptions with PFS disabled for pages.jumio.com


---
TLSv1.2 with PFS disabled
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.2";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


---
TLSv1.1 with PFS disabled
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.1";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


---
TLSv1.0 with PFS disabled
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionMinimumTLSVersion = "TLSv1.0";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


================================================================================


Configuring TLS exceptions with PFS disabled and insecure HTTP allowed for pages.jumio.com


---
TLSv1.2 with PFS disabled and insecure HTTP allowed
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionAllowsInsecureHTTPLoads = true;
            NSExceptionMinimumTLSVersion = "TLSv1.2";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


---
TLSv1.1 with PFS disabled and insecure HTTP allowed
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionAllowsInsecureHTTPLoads = true;
            NSExceptionMinimumTLSVersion = "TLSv1.1";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


---
TLSv1.0 with PFS disabled and insecure HTTP allowed
ATS Dictionary:
{
    NSExceptionDomains =     {
        "pages.jumio.com" =         {
            NSExceptionAllowsInsecureHTTPLoads = true;
            NSExceptionMinimumTLSVersion = "TLSv1.0";
            NSExceptionRequiresForwardSecrecy = false;
        };
    };
}
Result : PASS
---


================================================================================