Phals roots sometimes grow obnoxiously slowly and then other times they can just shoot out! I personally think they wait until we aren't watching
The white ring you see is the part of the root that is starting to mature into its "final form" that has the velamen (the spongy, water-absorbing part of the root) developing. In time, the root will be covered with this white-silver coating, and can be used as an indicator for watering b/c when it is that white-silver color, it's dry. Most roots will turn green when watered because the velamen absorbs the water and the green of the chlorophyll is able to be seen (more or less).
The new root's velamen will normally not change color from the white until it is older, so from the pictures you've posted, I would say it looks healthy and it only needs some more time.