Thanks for the plug 
Sometimes it helps to simply restart your local pc and also the slaves. Then in your camera view, switch to a different camera and back to the original. Now render and see what happens?
We had a VERY weird situation the other day where some boulders from a collection didnt render with textures on the slaves, even though the textures were in the same location and also pathed the same as all the other textures that the scene use. Ended up moving just that one texture to a different folder and repathing and only then it worked. Very weird. This was with max 2014 and vray 2.4
I’m hoping the auto asset collection in Vray 3.0 will sort all these weird issues