Heterogeneous volumes (VDB assets) sometimes refuses to render in movie render queue

Hey there, I’m a bit confused about the VDB lack of consistency in outputs.

I’ve got two sequences in which our camera drifts upwards into clouds passing text frames but depending on the time when I open/close Unreal the clouds either render or they do not.

Example of how the sequence looks in my viewport is below:

But now I’ve got to crunch time to output the video I can’t get the final clouds to appear in the rendered frames. Everything else it appearing but the clouds. It’s incredibly frusterating.

Occasionally they appear, sometimes they do not. There’s no consistency in how and when they will appear in my renders.

I’m not using pathtracer just standard renderer. Are there any final command I can use to ensure the VDB volumes will always be in the final outputs?

Thanks!