Dynamic Particles do not appear for fixed Nodes

[matt7ds]

Thanks for such an excellent project! I have run into this issue....

When I create nodes and links and specify

.linkDirectionalParticles(10)
.linkDirectionalParticleSpeed(d => d.value * 0.001)

as per the example, everything works fine.

However, if during the creation of the nodes, I specify values for fx, fy, and fz like this:

{id: "1", name: "Test Node 1", fx: "1", fy: "1", fz: 0 }

The Directional Particles are not present until the source node is dragged and dropped. At that point, the particles appear and animate correctly.

[vasturiano]

@matt7ds would you mind making a simple reproducing example of the issue, on https://codesandbox.io/ for instance?