Using Off-Hand to plant carrots/potatoes or any crop that grows on soil doesn't plant the crop and deletes 1 item. I can't see any reason to why it does this. 

Video: https://www.youtube.com/watch?v=SVmqkvH7Q2E

Re-produced this glitch off of lan world and produced the same result, this worked in 1.13-pre5.

The crop is not deleted, if you click on the stack or interact with the item stack, the item will show back up. It's just a visual glitch, but the crop should plant.