In an Old-type world, you cannot jump out of water 1 block deep onto a block that is in a chunk along the southern or eastern edge of the world. The problem does not occur in other chunks, including those on the western or northern edges.
Steps to reproduce:
Open the attached world MCPE-42417 demo.mcworld.
Go to coordinates -40, 62, 111 facing south. This is in water, just outside a chunk on the southern edge of the world.
Try to jump out of the water onto the block at -40, 62, 112. You do not succeed.
Turn right, facing east.
Try to jump out of the water onto the block at -41, 62, 111. You succeed.
Go to coordinates 159, 62, -126 facing east. This is in water, just outside a chunk on the eastern edge of the world.
Try to jump out of the water onto the block at 160, 62, -126. You do not succeed.
Turn left, facing north.
Try to jump out of the water onto the block at 159, 62, -127. You succeed.
We're already tracking this issue at MCPE-42058.