Hi Marion,
Your plant's healthy root system and single leaf reminds me so much of one of my phal survival stories.
A few years ago my noid phal had lost all of it's leaves with the exception of one big healthy one. It still had a great root system and I assumed the damage was due to moisture in the crown, although I always took great care when watering.
To discourage more rot and trauma, I left the plant in it's original container, but tilted it so that any residual moisture could drain. A basal keiki began growing a few months later. After it developed a few leaves I resumed the upright position of the pot it was growing in. What I didn't realize at the time was that our afternoon thunderstorms were pushing rain through the screen just a short distance away from where the plant was growing. To make a long story short, the basal keiki got wet and rapidly rotted. Oh, but there was still hope. That one remaining leaf from the original plant was still there and so were the heathy roots, so once again I tilted the pot and said a little prayer. Before long another keiki popped out. The photo below shows how the plant looks today. It still has heathy roots and the original leaf. Swelling near the base of the keiki indicates new root production. I've decided to keep this plant growing in the tilted position. When it pushes out more roots I plan to switch it to a mount. My mounted phals have never developed crown rot.
Good luck with your baby.
