As we suspected, the true cause of the problems people have been having with proxy objects turned out to be a bug in the OCS exporter code rather than in the proxy mechanism itself. This release should fix this.
Please test this and report any issues here.Octane Render for SketchUp x64Octane Render for SketchUp x64 (Demo)
Unfortunately the export bug has been in plugin releases for some time now (back to at least some of the early 0.14 releases, probably further). This means that most of the .ocs/orbx/obj files exported from any of these versions will be broken and cannot be re-imported as proxy objects; you will need to re-export them using the latest version of the plugin.