So I am trying to get some op librarians, and sometimes when I place down a lectern, a villager walks over it right  as I place it. After that, the block disappears, and then the next time I place a block, it is the lectern that disappeared, and the block that I tried to place winks out of existence. I have not seen if logging out fixes it, or if it works on servers, nor have I tested if it works with other blocks.