This bug appears in version 26.2 pre-release 3. The texture of the lava is completely black and the water becomes invisible.
Steps to reproduce:
Create a world in version 26.2 pre-release 3.
Place a bucket of water and lava in the world.
Expected result: The texture of the water and lava should be visible..
Actual result: The texture of the lava and water is wrong..
Environment
Intel(R) Core(TM) i5-3340M CPU @ 2.70GHz 2.70 GHz RAM 8.00 GB