N-Queens Algorithm tests problem

My function with the parameter n=1 returns the correct result - [[0]]. However, when I run the tests, this result is marked as an error. The same happens with tests 4 to 7. Could you please tell me what could be wrong with the output? Is there any way to find out what data the test expects to see in order to understand my mistake?

def dfs_n_queens(n):
    if n < 0:
        return []
    result = []
    stack = []
    for j in range(n):
        stack.append(j)
        visited = []
        def is_valid_location(index):
            row = len(visited)
            for i in range(len(visited)):
                if index == visited[i]:
                    return False
                diff = row - i
                if visited[i] == index - diff or visited[i] == index + diff:
                    return False
            return True

        def find_children_down():
            children = []
            for index in range(n):
                if is_valid_location(index):
                    children.append(index)
            return children

        while stack:
            current = stack.pop()
            if current not in visited:
                visited.append(current)
                if len(visited) != n:
                    children = find_children_down()
                    if children:
                        stack.extend(child for child in find_children_down())
                    else:
                        visited.pop()
                else:
                    result.append(visited)

    return result
print(f"result:  {dfs_n_queens(1)}")

Could you link to the challenge in question?

this challenge has some hidden requirements that make sure you are not hardcoding the results and not using global variables, if you continue working on the function you will eventually pass all of the tests, check for an input of 0,1,2,3,4,5 as those are listed in the tests

created an issue about this