Vanishing Pumpkins

While playing in a realm server created by a friend, I planted 4 pumpkin seeds and logged out. When I logged back in, they had all vanished. Only 1 seed "popped" out (discovered through research potentially due to poor lighting, but why only 1 of the 4?). However, when that last seed was planted in a well lit area + near water, the plant itself plus the farm plot vanished and was replace with a dirt block while I looked at it, maybe, 2 seconds after being planted. Nothing trampled it, jumped on it, etc. It just vanished.