Its undifferentiated plant tissue. Most often caused by using too much keiki paste or applying it more than once. The paste I have used says to apply it sparingly and only once as it is supposed to be waterproof. Don't know if yours is the same.
Keiki paste works best when the flower spike has finished its blooms and your plant is in an active growth cycle. Applying it when there are still blooms on the spike will generally, but not always, just produce another bloom spike.
Two videos that I've found appear to be promising in getting keikis without the use of paste and is something that maybe worth trying.