Keep watching. Most of the birds that use the upside down feeders will be like nuthatches, chickadees and various members of the woodpecker/flicker family. If you were expecting cardinals and finches they generally do not like to eat upside down. If there is enough side space in your feeder they might eat from the side but not bottom.

You might want to try haning it higher.

Try hanging it next to the other suet feeder. Birds that eat from the old suet feeder may eat from the new feeder and identify with its shape. Afterwards, you can move it a bit at a time to to new location.

In addition, make sure birds that you are feeding can use an upside down feeder. Not every bird can do it.

Paul