Linking a dx issue here as it was brought up there, and I cant fix it, but i figured out why
hmxmilohax/rock-band-3-deluxe#495
im no coder, but i looked in RndPropAnimHooks.c
rb3e checks if the anim frame is not 0, and if so, forces it to 2
which is correct BUT you must account for vocal players as well, as this will break certain circumstances
here is what we do in dx.

I have been banging my head on this issue but turns out its rb3e specifically.
and I cant fix it on my end as rb3e overwrites the anim frame
Hope this helps