You can trade with the green villager (nitwit) and it opens a empty trading window once per villager, closing the window and trying to trade again does nothing.
Command used:
/summon minecraft:villager ~ ~ ~ {Profession:5}
MC-106056
Can trade with /summon-ed green villagers (nitwit) only once per villager
Resolved
Fixed
8
(Unassigned)
Confirmed
Minecraft 16w32a, Minecraft 16w32b, Minecraft 16w33a
Minecraft 16w35a
Retrieved
If convert nitwit from a zombie villager to a villager there is no problem for me.
But if you summon him using the spawn egg you cant open hes gui.
the same problem if you get a baby of them(after he grow).