The warlock's Awakened Mind telepathy was recently changed from "You can communicate telepathically with..." to "You can speak telepathically to..." with the intent of clarifying that the telepathy was one-way.
Create Thrall's text, however, also says "communicate telepathically", but it has not been changed:
... You can communicate telepathically with the charmed creature as long as the two of you are on the same plane of existence.
Also, the Voice of the Chain Master invocation says "communicate telepathically with", and I have never played with a DM who prevents a Chain warlock from two-way comms with its familiar:
You can communicate telepathically with your familiar...
Does this imply that the warlock enjoys two-way telepathy with its thrall?