I'd say your tune is not yet complete. Take a look at the file '2016_ss_flex_fuel_baseline.zip' found in this thread.
https://www.camaro6.com/forums/showthread.php?t=469951
You can find this info in the changelog.txt, but overall you need to change the following below. It has worked great for me, but make sure your HPT software UI is in "advanced" mode to find all relevant values.
- modified Engine -> Fuel -> General -> Air Fuel Ratio -> Stoich AFR-> Flex Fuel AFRs *(use values from .hpt compare file)*
- modified Engine -> Fuel -> Open & Closed Loop -> Flex Fuel -> Flex Fuel -> Enabled
- modified Engine -> Fuel -> Open & Closed Loop -> Flex Fuel -> Flex Fuel -> Fuel Sensor -> Sensor
- modified Engine Diag -> DTC's -> P0178 -> Flexible Fuel Sensor Circuit Low -> checked, Error Mode -> MIL on Second Error
- modified Engine Diag -> DTC's -> P0179 -> Flexible Fuel Sensor Circuit Low -> checked, Error Mode -> MIL on Second Error
- modified Fuel Sys -> Diagnostics -> Flex Fuel -> Sensor Diag -> Enable
*** optional ***
- modified Engine -> Spark -> Advance -> Spark Correction -> AFR Correction -> Alcohol -> Gas table
- modified Engine -> Spark -> Advance -> Spark Correction -> IAT Spark -> Mult4 -> [1.00 1.00 0.80 0.50 0.20]
- modified Engine -> Spark -> Advance -> General -> Cranking/Start -> Cranking -> enhanced for Flex Fuel
- modified Engine -> Spark -> Advance -> General -> Cranking/Start -> Alcohol Adder -> timing added for Flex Fuel cold starts
For any reason if this doesn't work, make sure the white cable is connected ALL THE WAY IN. Good luck!