This may come from your converter. I have the same issue with one particular HDMI-Ethernet-HDMI extender set. One solution is to convert the HDMI signal to component and bring it in to the computer that way. You may just have to try different converters until you find the one that works for you.

I had the same issue trying to capture the output of an Android tablet. What I did to get around it was split the HDMI and feed one leg to a monitor. That satisfies the HDCP handshake. The second leg then fed an HDMI capture card in the vMix host.

I've also used this approach with an iPad.

Michael

It has absolutely nothing to do with the software.

vMix does not restrict protected content. HDCP (High-Bandwith Digital Content Protection) is meant to stop HDCP-encrypted content from being played on unauthorized devices or devices which have been modified to copy HDCP content. It must prevent transmitting high definition protected video to non-HDCP receivers. A capture card or a HDMI to SDI converter is a non-HDCP receiver and exactly the devices that get blocked because you can use them to make a lossless copy of the content, which is exactly what HDCP was made for to prevent!

The hdmi to sdi converter in your setup is where it goes wrong. SDI can not have HDCP so the converter cannot convert the signal. If you would put it directly into a HDMI capture card it will also not work, as the capture card is not allowed to unscramble the hdcp signal, because it is not a sink(single display).

So you should either get rid of the hdcp signal on the iphone, or build something into the stick that does get rid of the HDCP like the splitter I showed you.
There are also HDMI to SDI converters that do not comply with the HDCP rules, but I have no example for you that works guaranteed, as the ones I have that can do this are a few years old aready. Most of the time the ones that can do this are very cheap brandless chinese products.

Add this since it didn't get mentioned previously. There are little HDMI plugs that are monitor emulators. Their function is to satisfy the output device that a monitor is connected.

They are often required if you'd like to us a desktop sharing tool, like VNC, to connect to a computer that for practical reasons, doesn't have a monitor physically connected. I'm told that this is dead common with the Mac Mini.

If you're trying to overcome HDCP you can use one of these emulator plugs on one side of the HDMI splitter.