Unfortunately it is usually common for stems to melt when put in a substrate. All I can recommend is that you leave it floating until it grows roots, then trim the plant to where the roots are and plant.
Its pretty new, maybe only a week old in my tank.
If it keeps comming up, I might just let it float tbh.
Only other plant giving me issues is L. inclinata var. Pantanal....which I hear is KNOWN for being a pita so I expected that
Only got my blyxa to stay put with the use of mesh
Hm, my Tonina melted at the bottom when I first got it. It didn't get unrooted and is growing really well now. I'd say that this is typical, but I'll be able to tell why I get some brown hygro this week.
My Golden Rule of planted tanks: WWTAD-
"What would Takashi Amano do?"