Block shadows prevent Screen-Space Reflections from properly rendering in the Deferred Technical Preview

In the deferred rendering technical preview, block shadows (ie. the simple per-block shadows that impact actual in-world block light levels, as opposed to deferred lighting's real-time shadows) cause screen space reflections (SSR) to render incorrectly, causing strange visual artifacts whereby shadows appear white. In standard gameplay, this issue is visible whenever blocks overhang a body of water, and is especially obvious underground in caves.

The issues persists even if the blocks causing the shadow are far above and off-screen, implying that it is not a technical limitation of the SSR tech. But if there is a technical reason behind the issue, then the shadowed areas should be made darker rather than lighter.

Steps to reproduce:

• Import the included example world file (which includes an example deferred pack), and look toward the cobblestone overhang above the water.
• OR: Apply any deferred lighting-enabled texture pack that has water reflections properly configured, and find an area of water that has blocks above it.

Observed behavior: the shadowed area appears very bright and lacks the correct environment reflections.

Expected behavior: the water should reflect its full surroundings regardless of whether there is a block shadow on it. If this is infeasible, block shadows should cause water to darken rather than lighten.