Does not work on Pixel 2 or 3 on (.0/Pie

I've allowed the app to draw on top of others/system, but the sliders do nothing, there's no overlay or darkening of the screen.

It *used* to work find on my Pixel 2 but there was an update end of last year I think which broke it so it wasn't an Android update.

Any chance this can be amde to work, as the info in the app windows implies it can work