The bug

While water has six faces which it renders on the outside, only five of them have equivalent inside faces. The sixth face (the bottom) will never render from above/inside of the water block.

Note that the provided screenshots do not show side faces for water either in most cases - this is a result of MCPE-34085 (a ticket which should also be given the fluid-geometry and missing-planes labels). Unlike that ticket, the bottom face is not nonexistent due to any underlying blocks, as can be seen by breaking the pressure plate in the setup and noting that for the instant in which no block is below the water, there is also no bottom plane.

How to reproduce

1. Create the setup shown in the screenshots
2. Enter the water block

Expected results

The bottom face of the water would be visible.

Actual results

It is not.

How to fix

When Bedrock Edition finally gets block models, it should get fluid models as well - planes could be defined for these faces such that they actually exist.