Backtracking recursive search function

Question

Im having issues backtracking through a list of lists in order to solve the Skyscraper puzzle. My goal is to try an element, filter out the board after that element has been inserted , and check if the new board is valid, if it is , continue, if not, try another value.

My board structure is the following: I have a 6 by 6 list of list, each item of the sublist is another list with all the possibilities from 1 to 6. When i have a list of length 1, that means that the element inside is the only possibility, and so it becomes an int. Example of a row in a 3*3 board: row = [[1,2] , [1,2] , 3] (of course in this example, the board would have 2 more rows)

Here is what i have so far, i dont understand why it doesnt work.

def search(searchBoard, clues):
    print_board(searchBoard)
    if not full(searchBoard):
        return searchBoard
    row, col = full(searchBoard)
    for i in searchBoard[row][col]:
        next_board = copy.deepcopy(searchBoard)
        next_board[row][col] = i
        if valid(next_board, clues , i , (row,col)):
            search(recElim(next_board , 6), clues)
    return False

def valid(board, clues, num, pos):
    row = [num if i == pos[1] else board[pos[0]][i] for i in range(6)]
    col = [num if i == pos[0] else board[i][pos[1]] for i in range(6)]

    if row.count(num) > 1:
        return False
    if col.count(num) > 1:
        return False

    clue = clues[pos[1]]
    if clue != 0 and clue not in make_permutations(col):
        return False

    clue = clues[pos[0] + 6]
    if clue != 0 and clue not in make_permutations(row[::-1]):
        return False

    clue = clues[::-1][pos[1] + 6]
    if clue != 0 and clue not in make_permutations(col[::-1]):
        return False

    clue = clues[::-1][pos[0]]
    if clue != 0 and clue not in make_permutations(row):
        return False

    return True

Search: Search is my main backtracking function.

Valid : Valid checks if the new row with the now inserted integer is valid or not.

Full : Full checks if there are still elements to place in the board or not, if not, it returns None, else it returns the tuple (i , j) (the coords of the cell to fill)

recElim : This function has 2 roles:

1: Removes values from the list of possibilities if those values are already inserted in the row
2: If in a list of possibilities, there is one element that none of the other sublists have, then it inserts that element

make_permutations : Lastly, this function returns all the possible clues that are valid depending on the row

While debugging, my function seems to be doing all the permutations (even finding the right answer) but just continuing until its done all of them. Then, it returns the board unchanged. What i would want is for it to find and return the correct answer without calculating all other permutations