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.