Sheep & Boat both disappear upon the Player dismounting the boat. (Visible Shadow)

I was cruising on my boat through the river admiring the view, a sheep decided to get on the boat before I mounted and upon dismounting to expand a narrow gap I figured both the sheep and boat have despawned. In response, I crafted another boat cruised around and saw another sheep, which I lured while on the boat with wheat on my hand, it hopped on. I rowed back to the expanded river gap and the previous boat and sheep have reappeared. I decided to take the new boat back and sadly knocked out the 2nd sheep. After I arrived to the coast, I dismounted and yet again the sheep and boat have disappeared. However, I finally noticed that the shadow of the boat is still visible, but the sheep is rapidly teleporting around far away diagonally and back to the boat's position.