GPU Debugging - incorrect Pixel Shader Output

I'm trying to diagnose an issue with incorrect colors coming out of a pixel shader. Using the GPU Debugger in Visual Studio 2017 (DX11), I can capture a frame and debug an individual pixel. In the Pixel History, I can start debugging the pixel shader and stepping through I see a particular output color. In the next section, Output Merger, it shows "Pixel Shader Output (SRC)", followed by the color that was output by the pixel shader. However, sometimes these values do not match. Debugging the pixel shader will show one value as output, and the Output Merger will report another color being output (this color is what ultimately appears on screen).

From a straight-on angle, this bug appears as incorrect colors, and will change based on distance to the camera. From an off angle, I see Moire effects across several of my colors (defined in a float4[] uniform I'm using as my color palette) all over the geometry I'm rendering.

If anyone has ideas for why a pixel shader output wouldn't match the actual PSO(SRC) shown in the Output Merger, please help.