Yes it was skin cache, not only ray tracing. I saw this post before and turned off ray tracing, but that in itself didn’t help. I uncheck the “support skin cache” checkbox and it works! Since ray tracing requires skin cache to be enabled, it will also have to be disabled. But everything will work even if the stage is full of modular characters with set leader poses and rigs (metahuman hasn’t checked it yet). In any case, thanks for the tip!