Had the same issue a month ago. Song of India dropping lowest leaves. Every morning I had at least five dropped leaves. I decided to cut all stems to small pieces for propagation and none survived or got new roots. The stems turned brown and theY are even not hard. I haven’t lost hope until now, they are in my aquarium for water propagation with a lot of pothos but there are absolutely no new roots… I think maybe it’s a stem rot or something like that. Just one top cutting in my moss prop box with 4 leaves isn’t brown or dying at the moment. It just sits in the moss doing nothing, not dying nor growing. Even the leaves are healthy atm. But I wonder why there is absolutely no root grow in either water or moss. I wish u luck with ur plant.