Do Lands count as permanents? Did I find a bug in Magic Arena?
Lands are colorless permanents, so they will not cause you to draw any cards with Chromatic Orrery.
This is a result of rule 202.2:

202.2. An object is the color or colors of the mana symbols in its mana cost, regardless of the color of its frame.



202.2b Objects with no colored mana symbols in their mana costs are colorless.


Lands have no mana cost, so they have no colored symbols in their mana cost, so they are colorless.