I recently had what sounds like a similar problem but in Vue2014 where using the ecosystem painter made a house seemingly disappear.  I raised a ticket at e-on and Lee checked my scene file and confirmed that the house disappeared.

Their tech people looked at it and it was the simple fact that both myself and Lee were zoomed out too far.  The underlying ecosystem generated lots of tiny green dots representing the grass layer and those dots were obscuring the house.  Zoomed in and the house became visible.

Not sure if this is the same as your problem but posted just in case

Gill