I would suggest you to to do a quick test using the Forest Tools
utility to export all scattered geometry into instances. You can find it under Utilities
- More ...
- Forest Tools
. For more information about it, check our on-line reference guide
. This way you can check that the problem happens during Forest object conversion or not.
Anyway, it sounds like that probably it'll be a backburner related issue. Unfortunately that error is generic and doesn't give us a hint, where the problem could be. In many cases it might be related to "Consistency in versions is important on manager, render slave, and 3ds Max workstation. The same version of 3ds Max + Backburner should be installed, including Service Packs, Hotfixes, Extensions, and plugins."
Would you please specify which renderer (and its release) are you using?
I would suggest following steps, which might help:
Backup & remove any files under C:\Users\*username*\AppData\Local\Backburner\ServerJob
Backup & remove UI files under C:\Users\*username*\AppData\Local\Autodesk\...\ENU\en-US\UI
Regarding the XRef Object Merge: Units Mismatch
warning window: Because of the importation process slightly changed, that message is triggered while working with the 3ds Max 2016 (even it's actually merging items/models and not linking them as XRefs). Anyway, upon our testing it behaves correctly (when using any geometry from scene with different Scene Unit Setup it´ll rescale the geometry accordingly). I would suggest you always leave the default option Rescale the XRef Objects to the System Unit Scale
We've already contacted Autodesk regarding it, but it doesn't seem there is a possibility to avoid that "confirmation" step.
Please let us know the result of "Forest Tools test" and if restoring UI / job queue helped or you are still facing troubles with it. Thanks in advance and have a nice day.