Hi, we just released Forest Pro 5.1.3 beta
with additional log options.
To enable logs, just set General->Log Level
in one of the Forest objects, before sending it to render (local or Backburner).
This update doesn't change anything in Mental Ray, but may help us to identify the rendering problems.
There are two logs. One generic for Max at:
C:\Users\<user name>\AppData\Local\Autodesk\3dsmax\<max version>\ENU\Network\Max.log
and other specific for Mental Ray in Rendering->Render Message
window (local rendering), or included in the Backburner logs. For backburner, just be sure to enable "Info" level as shown in the attached image.
Logs are created locally for each render node.
Please, install the update and send us the log for nodes which don't render correctly.