Perhaps a different issue. I only guess this because I use another Octane plugin for a different software, Carrara.
It also has this reload texture issue. In the case of Carrara, reloading the scene updates the texture, and the reload button does nothing, like now with Blender.
But that said, the Carrara plugin displays none of the issues you describe.
One annoying workaround for Blender reload: insert the wrong texture - one you don't want, and then insert the correct texture. This updates the render preview.