As the title say, Dryer does not want to place even when green when in Creative mode. Its very finicky; it will place every once in a while, but it really does not seem to work well. All the other pieces seem to be performing normally – its just the Dryer that doesn’t want to cooperate.
EDIT: it may be been due to a rock protrusion that the game was not accurately detecting. It would register green, but wouldn’t place. Putting a Dryer on the other side of my base next to a wall seemed to do fine. So it may only be a collision detection issue.