Rear soiling and rack shading losses for bifacial modules

Adjusting the bifacial rear soiling and bifacial rack shading parameters doesn't appear to be impacting the results of my simulation. I've created a small, one row bifacial system with a relatively high array height to emulate a portion of a carport, but after running the simulation the waterfall chart shows no losses due to rack shading or soiling on the back of the array. This remains the same regardless of the values that I input for rear soiling/shading. Am I missing something here?