My Hellcat bone stock didn't like much below 1/2 tank and I'd see the bypass open in logs. Maybe the 2 pumps in the Demon are holding a little more fuel in the bucket avoiding that issue.
On your starting problem, it sounds to me like the lines aren't holding fuel after shut down. If it fires right up after priming it, that would be a clue. Maybe someone with the TI295 pumps can chime in since those don't have check valves and describe their startup characteristics.
@16GoManGoHC2 runs the 295s.
Alternatively the fuel trims could be off due to the methanol mixed fuel, but I'd expect a code if it were bad enough to cause a starting issue.