The middle layer is not providing any useful values for design so make sure you use min/max values for outer layers. Also, pile caps behave differently than plates/shells so a strut and tie method is more appropriate than plate analysis.
Why did you create 2 cases for Dead Load: DL1 and DL2? Both of them take into account the selfweight? I am new to Robot. Always used SAP2000. Any tip will help!