This is interesting..anyone noticed this problem with their Osno action fitted with ND filters?

Yes EIS / rocksteady also need to be able to see stuff to work.
So you cant go too creative when you also have movement of the camera, at least not without also getting a gimbal, and to me at least thats also just fine, as long as people know this and what to expect.

Right now, RockSteady needs faster shutter speeds. They have said this is being addressed and will be optimized in an upcoming firmware update.