why hidden fumeFX are rendering?

[jrand]

Hmm that is interesting.

Just tested it and I can confirm it:
1. Create a grid add source and simulate
2. Render
--Fume is visible in VFB
3. Hide Fume Grid
4. Render
--Fume is NOT visible in VFB
5. Unhide Fume
6. Hide Fume
7. Render
--Fume IS visible in VFB

So after the first set of hide/unhide actions the Fume Grid seems to remain in an Unhidden state.

Resimming seems to reset the behaviour. You can, for instance, resim, hide it once without it rendering, then hiding/unhiding subsequent times the issue seems to re-occur.