The return value of int64 FMath::RandRange() is biased

Repeat the following process to check the log output

const int64 min = 1000000000;
const int64 max = 9999999999;
const int64 x = FMath::RandRange(min, max);
UE_LOG(LogTemp, Warning, TEXT("int64:%ld"), x); 

Output will be "-1147483648" with high probability (71 out of 100 times).

TruncToInt64() should be used in RandHelper64() instead of TruncToInt().