I can't check extra test

I check and look on to http://www.pythontutor.com/visualize.html gonna sometping strange. Cycle for work 3 time and continue to next block. And i don't understand wy. Help, please. P.S. Sorry to my ugly code.

   def house(plan):
        spisok = plan.splitlines()
        if "" in spisok:
            spisok.remove("")
        counter = 0
        for element in spisok:
            for element2 in element:
                if element2 == "0":
                    counter += 1
                    if counter == len(element):
                        spisok.remove(element)
                        counter = 0
                    else:
                        continue          
                else:
                    counter = 0
                    break

    counter = 0
    spisok2 = []
    while counter != len(element):
        x = [item[counter] for item in spisok] 
        spisok2.append(x)
        counter += 1

    counter = 0
    for element in spisok2:
        for element2 in element:
            if element2 == "0":
                counter += 1
                if counter == len(element):
                    spisok2.remove(element)
                    counter = 0
                else:
                    continue          
            else:
                counter = 0
                break

    return (len(spisok2))*(len(spisok2[0]))

if __name__ == '__main__':
    print("Example:")
    print(house('''
0000000
##00##0
######0
##00##0
#0000#0
'''))

    #These "asserts" using only for self-checking and not necessary for auto-testing
    assert house('''
0000000
##00##0
######0
##00##0
#0000#0
''') == 24

    assert house('''0000000000
#000##000#
##########
##000000##
0000000000
''') == 30

    assert house('''0000
0000
#000
''') == 1

    assert house('''0000
0000
''') == 0

    assert house('''
0##0
0000
#00#
''') == 12

    print("Coding complete? Click 'Check' to earn cool rewards!")