That's not a bug.
If you choose the dialog's 'Render Frame' it exports the OBJ File [with supporting MTL/texture-files etc] and then runs a 'cmd' file that uses that data in an Octane OCS - i.e. using whatever camera, shadows etc that you have set in the dialog. It is of course possible to do this with no camera set, so that the default Octane camera is then used.
If you choose the export the OBJ/MTL only etc only there is no render done: if you open this OBJ in an Octane OCS there is no camera data with it. An OBJ file contains' geometry info' and the MTL has the associated 'materials/textures' etc - there is no camera or shadow settings etc in these types of file - so you must either set these manually OR activate Octane via a 'cmd' file that passes suitable details to it as it runs.
Thus when you choose "Render Frame" from the dialog you pass whatever settings you have ticked from the SKP to the OCS - typically the camera.
BUT running an OCS on a 'raw' OBJ will have no built-in camera data at all...
Octane is not psychic.........