I think I found the problem answer. I locked the modo camera, so it can stay in place for the render, and because of this all its parameters locked, including octane render, this is why the popover didn;t appear. is there a work around to have the modo camera locked, and the popover appear.
This looks like a Modo limitation. I have a work-around which will be in the next release. You can also lock just the camera position, which will fix your immediate problem.
Also, Paul how about instead of pop over, we will get side menus on the property list as modo and vray has implemented.
The first release of the plugin had the camera settings in the tab side menus, but all the beta testers wanted it as a separate panel - since there was so much information in there, so that's why the camera info is in a panel - which I think works better than a tab.
Paul