The problem is that in this object some of the points have defined an "instance" point attribute with an empty string. Due to this attribute, the plugin thinks that this object is an instancer, but of course, it can't find the object to be instanced. To avoid this problem you need to delete this not used "instance" point attribute.
Hope it helps,
Computer Graphics Software Developer
Octane plugin development and support: LightWave and Houdini