I encountered this problem as well, and as a quick fix, I opened Niagara in Unreal 5.3, added the Vortex Velocity module, and opened it by double-clicking it. Then, I copied the entire script into a Niagara Module Script and imported it into my Unreal 5.4 project.
It works perfectly.
I’m posting this here in case anyone else might need it.
NM_VortexVelocity.uasset (70.3 KB)