Not sure if this is helpful to anyone, or even 100% the same issue, but my search for compile errors with LiveLInk brought me here so maybe worthwhile for someone down the line?
I was also getting the below compiling error as you can see per the screenshot (project worked fine before, but I had to dump some metahuman control rig files in the trash to regain control to a corrupted control rig system).
I am not really using the live link system at the moment, but did not want to delete the function in case I want to use it for facial animations later. So, I brought a metahuman in to a new project and pulled up the same function, and this is what it gave me.
Comparing the two some of the casting nodes went bad probably when I dumped the files. Once I rebuilt that function with the proper nodes everything went back to normal.
Iām running UE 5.4.4 with MetaHumans and still encounter the same issue. After reopening the uproject containing MetaHumans, Face_AnimBP has compiling issues regarding LiveLink. Although the nodes are not totally gone!
The hotfix is to delete all C++ GameModes, which reference classes with Skeletal Meshes having Face_AnimBP as Anim Class. Create a Blueprint GameMode, assign the same values as in the C++ GameMode and set it in Project Settings > Project - Maps & Modes > Default GameMode. Maybe you have to check World Settings > Game Mode > GameMode Override aswell for any side effects. After recompiling (via IDE or by deleting Binaries/Intermediate folders) and reopening, Face_AnimBP should be fixed.
The next issue I have is, that On Anim Initialized (Face) is not called for the DefaultPawn, but for the exact same Blueprint spawned on the map. Another hotfix is to call ARKitFaceSetup and SetUpdateAnimationinEditor in BeginPlay, too.
