When I run in my terminal and input a location, I keep getting "That's not a valid location".

from cards import Card
import random


class Game:
    def __init__(self):
        self.size = 4
        self.card_options = ["Add", "Boo", "Cat", "Dev",
                             "Egg", "Far", "Gum", "Hut"]
        self.columns = [" A", "B", "C", "D"]
        self.cards = []
        self.locations = []
        for column in self.columns:
            for num in range(1, self.size + 1):
                self.locations.append(f"{column}{num}")

    def set_cards(self):
        used_locations = []
        for word in self.card_options:
            for i in range(2):
                available_locations = set(self.locations) - set(used_locations)
                random_location = random.choice(list(available_locations))
                used_locations.append(random_location)
                card = Card(word, random_location)
                self.cards.append(card)

    def create_row(self, num):
        row = []
        for column in self.columns:
            for card in self.cards:
                if card.location == f"{column}{num}":
                    if card.matched:
                        row.append(str(card))
                    else:
                        row.append("   ")
        return row

    def create_grid(self):
        header = " | " + "|  ".join(self.columns) +"|"
        print(header)
        for row in range(1, self.size +1):
            print_row = f"{row}|"
            get_row = self.create_row(row)
            print_row += "|".join(get_row) + "|"
            print(print_row)

    def check_match(self, loc1, loc2):
        cards =[]
        for card in self.cards:
            if card.location == loc1 or card.location == loc2:
                cards.append(card)
            if cards [0] == cards[1]:
                cards[0].matched = True
                cards[1].matched = True
                return True
            else:
                for card in cards:
                    print(f"{card.location}: {card}")
                return False

    def check_win(self):
        for card in self.cards:
            if card.matched == False:
                return False

    def check_location(self, time):
        while True:
            guess = input(f"What's the location of your {time} card? ")
            if guess.upper() in self.locations:
                return guess.upper()
            else:
                print("That's not a valid location. It should look like this: A1")

    def start_game(self):
        game_running = True
        print("Memory Game")
        self.set_cards()
        while game_running:
            self.create_grid()
            guess1 = self.check_location("first")
            guess2 = self.check_location("second")
            if self.check_match(guess1, guess2):
                if self.check_win():
                    print("Congrats!! You have guessed them all!")
                    self.create_grid()
                    game_running = False
            else:
                input("Those cards are not a match. Please enter to continue")    
        print("Game Over")       


if __name__ == "__main__":
    game = Game()
    game.start_game()