It's happened to me only a few times in my forty-five year career.
I start one side of the lane and point to the lowest marked lane space and stongly ask, "Who (defense) wants this spot?".
Move onto the next marked lane space and stongly ask, "Who (offense) wants this spot?".
Then I switch to the other side of the lane and do the same.
Then I switch to the more distant marked lane spaces and do the same with defensive players.
Then I very stongly state, "Nobody move!" and we play on from there.
I'm not sure what I would do it they didn't follow my instructions because they (luckily) never did, but I'm sure that I could come up with some penalty.
The key is to use a strong, confident voice (like it's the real rule).