Dracena Marginata stems collapsed
I have two Dracena marginata plants. One is just a single stem, and I have had it for 8 years and reported it 3 times, it is now in an 8" pot. It slowly keeps growing, though it is still under 1 foot tall. It always seems to do well.
The newer one is another small one, but the single steam breaks into three separate stems with leaves. It has been that way for the two years I have had it. It came in a 4" pot and I just moved it into an 6" pot. I used the same soil for both of them.
The newer one with three stems started have its leaves turn yellow a few weeks after re-planting, then all three stems started to wilt and eventually fell over. When they fell, the outer bark ripped, and the inner stalk in all three is thick, black, and rubbery. Sort of looks like licorice rope. Any idea what happened to it, and is there a way to recover it?