the disappearing field container happened to me too.
i've moved to a place where i have successfully deployed field containers before. the dialog for the code pops up, i enter a code, the dialog closes and then the field container gets removed from the bot's cargo but doesn't appear on the ground.
it is kind of annoying when you travel some distance with a slow mining bot and then have to return because the field container simply disappears and you didn't take a second field container with you.
as this is a random bug there is no evidence (screenie, video, ..) that i can post. i think that it should be possible to search the game's database for deployed but unused (never opened) field containers.
EDIT: maybe add some timer which checks if the field container was successfully deployed. if not, then return the container to the cargo so the user can try again.