ok, here is a thing, actually we have faced this problem before aswell (in 1.7) and now in daily with different scenarios and different scenes.
We extensively use forestpack plug in from itoo software, and when we render, everything is fine, but as soon as we enable distributed render (not always, for example we did a batch render for around 10 shots, and only some of them had the problem) the forest objects are transparent. We thought it was an license issue, but forestpack actually doesnt require license for DR machines, but still we tried on the main computers which has their license active, but still, it sometimes occur, sometimes doesnt. We hoped it would be fixed in dailies, but still happening. So is there any ideas? And weird thing is, we see this a lot, but couldt find anyone asking for it.
Any ideas?