Phal grew new roots but all browned

[Irisha99]

Hi, guys.
This Phal had two thick roots you can see on the bottom. I decided it needed to grow some new ones and I put it in bark and wrapped the base of it in sphagnum moss. I kept it nice and moist. 5 new roots grew and were doing well, however, then they just stopped growing further and became a bit browned. I put it in KelpMax solution every month. Don’t know what to do with it now. For some reason it always happens like this when I try to grow new roots. They grow and then brown... any idea what happens with them? Too much moisture? Thank you