My F800S used to do the same thing, and I also do a lot of engine braking. I have learned to avoid the problem by shifting from 2 to 1 while the engine is still spinning above 2.5 K rpm. If you let it get below that, it can be harder to shift into first or neutral.
I really don't recommend you stomp on the shifter. If rolling back and forth or feathering the clutch doesn't help, just turn off the engine. The clutch is probably dragging a bit, and if the engine is not spinning, you can probably shift into whatever gear you want with light pressure and some rolling around.
I also found it helped to put extra slack in the clutch cable. You would think you would want less slack in order to be able to disengage the clutch more. But I think less slack tends to heat the clutch more, causing it to be sticky.