Live Link ARKit animation issues in Unreal 5.7 - can't get device recognized, "Subject is invalid"

Hi All,

I am having trouble using Live Link’s ARKit fuction for animating characters in Unreal 5.7.

My iPhone is successfully connected to Unreal Engine and if I choose it under the “Live Link Face“ option in the Live Link menu while my app on the phone is in Metahuman Animator mode, the device gets a green tick and I can effortlessly animate any Metahuman characters. However, as soon as I switch to the ARKit mode, a yellow error box appears, saying “Subject is invalid“ (screenshot below).

I’ve checked the Unreal 5.7 documentation, which says that the phone should be switched to Metahuman Animator mode for Live Link Face to work - but how is it possible to do facial animation for non-metahuman characters then? A lot of the great Fab characters are compatible with ARKit rather than MetaHuman, due to their 52 blendshapes.

I have gotten the legacy feature to work a few times and managed to record some animations via ARKit, but it seems to have been a fluke, and I can’t replicate it or get it to work reliably.

Does anyone know of solid documentation on using ARKit with newer versions of the engine? I have found very few tutorials, most of which are serveral years old. Or am I missing something very obvious on using the ARKit function?

Thanks in advance!

Realized I completely misunderstood the setup of the ARKit, which didn’t go through the Live Link Face source at all. Think I managed to get the hang of the basics, so I created the type of tutorial that would have helped me to get started - if anyone is confused, hope this comes in handy. Links to Epic’s relevant documentation and guides are included in the video description.

Live Link ARKit Basic Tutorial