Stem plant roots rotting

I need help I've had this tank setup since the start of December and I have been trying to let it cycle before I put any fish in it but I've run into an issue with the stem plant I planted in there. I planted red ludwigia, blood sg and rotala rotundifolia. My red ludwigia is doing good but I noticed the blood sg and rotundifolia roots are rotting and some have become slimy and smell. The water has also been murky but i figured since it was a new tank it was likely an algae bloom but im not too sure at this point. I don't know what's wrong with them but I would appreciate any help.