Guess I've read it somewhere on the to-do list but don't expect it to be enabled fast
Also in this case it is not about the grader being picky or about things that a linter or beautifier could solve. The problem is that the results differ from the expected.
If you have a look at your first approach and go through it with a value of 15 you'd get 3 result because all "Fizz", "Buzz" and "FizzBuzz" are printed. If you'd now go with the suggestion to replace the 3 ifs with a row of if/else if ... then you'd only get one output but that would be the first matching case: "Fizz".
So this is only true for numbers that are not divisible by 15.