Yes. But you're not missing out on much. What you can obtain from them is quite limited. However, it is a nice money source (at least while the game is relevant) since you can put one item up for sale and the adjutant will sell it indefinitely.
Gamefaqs resident here. Myself and another member put together this post: https://gamefaqs.gamespot.com/boards/204445-fire-emblem-three-houses/77938108 Hope it helps. Feel free to put whatever you want up on this awesome site.