I found that if I use a particle generator in the scene (in Octane_Object_Properties, the Particles tab), then when exporting a scene to ORBX, the instances based on them do not work, while in LW it works quite reliably.
There are instances here:
Standalone Octane. Here the instances have disappeared:
AMD Threadripper 1950X/64gb ram/RTX 3080 Ti + RTX 2070/Samsung SSD 870 EVO 500 gb/
Lightwave 3d