I have a ficus elastica that has always struggled to keep its leaves. At first, they appear healthy but after they are full-size their edges dry out and the entire leaf eventually falls off. The edges become totally dry, like a hard, dry bay leaf that you’d cook with. I have read about too much light, too little light, too much water, too little water…I’ve repotted, moved it around, tried a variety of locations over a number of years and nothing seems to help. The top continues to grow but older leaves fall off and it’s turned into a long stick! Any clues?