The ice cube trick does help for homeowners (we don't typically have time to wait for ice to melt). But I've tried it on my own carpet, after the ice cube has melted into carpet, use a fork to lift the fibers up.
Usually when I'm cleaning (after explaining to the homeowner that they won't come out completely due to stretching of backing and compression of pad) I'll hold the wand over the indents a few inches off the carpet and just spray the area with the super hot water and let it soak while I start cleaning the room and by the time I get to the spot the backing and fibers have relaxed to the point where it looks a lot better, not perfect but it helps.