i cant find the problem in palindrome recursion c

I have a problem with my program, in this code, I need to check if a string is a palindrome with recursion but for some reason, if the string length is even and every other char but the middle are similar then it should still work (like aaaaaabCaaaaaa)

    #include <stdio.h>
    #include <string.h>

    #define EMPTY_STRING -1 
    #define FALSE 0
    #define TRUE !FALSE
    #define MAX_STR_LEN 500

    int isPalindrome(char str[], int start, int end);

    int main(void)
    {
        char str[MAX_STR_LEN] = "some random words that will get over-drived like eggs, plane, chair and a young unicorn that jumps on the bad";
        int end = 0;
        int start = 0;
        printf("please enter the string you want to check: ");
        fgets(str, MAX_STR_LEN, stdin); //getting the string
        str[strcspn(str, "\n")]; //removeing the \n from the end
        end = strlen(str) - 2; //removing the null (And another char that i dont know how it got there)

        if (end == EMPTY_STRING) //checking if its an empty string, if it is then printing yes
        {
            printf("palindrome");
            getchar();
            return 0;
        }

        if (isPalindrome(str, start, end)) //checking if the string is a polindrom
        {
            printf("palindrome");
        }
        else
        {
            printf("not palindrome");
        }

        getchar();
        return 0;
    }
    /*
    function gets a string and checks if its a polindrom
    input: the string, the first char index. the last char index
    return value: true if its a polindrom, false if its not
    */

    int isPalindrome(char str[], int start, int end)
    {
        int isPalindromeTrue = FALSE;

        if (str[start] == str[end]) //if the  chars are matching , continue
        {
            isPalindrome(str, start + 1, end - 1); //callingn the function again
            isPalindromeTrue = TRUE; //will be used after all itertions
        }

        return isPalindromeTrue;
    }

You may use this code. Here I deleted this redundant line str[strcspn(str, "\n")]; and added a new if condition for the case of an "even" string:

#include <stdio.h>
#include <string.h>

#define EMPTY_STRING -1
#define FALSE 0
#define TRUE !FALSE
#define MAX_STR_LEN 500

int isPalindrome(char str[], int start, int end);

int main(void)
{
    char str[MAX_STR_LEN] = "some random words that will get over-drived like eggs, plane, chair and a young unicorn that jumps on the bad";
    int end = 0;
    int start = 0;
    printf("please enter the string you want to check: ");
    fgets(str, MAX_STR_LEN, stdin); //getting the string
    //str[strcspn(str, "\n")]; //removeing the \n from the end
    end = strlen(str) - 2; //removing the null (And another char that i dont know how it got there)

    if (end == EMPTY_STRING) //checking if its an empty string, if it is then printing yes
    {
        printf("Yes");
        getchar();
        return 0;
    }

    if (isPalindrome(str, start, end)) //checking if the string is a polindrom
    {
        printf("palindrome");
    }
    else
    {
        printf("not palindrome");
    }

    getchar();
    return 0;
}
/*
function gets a string and checks if its a polindrom
input: the string, the first char index. the last char index
return value: true if its a polindrom, false if its not
*/

int isPalindrome(char str[], int start, int end)
{
    int isPalindromeTrue = FALSE;

    if (str[start] == str[end]) //if the  chars are matching , continue
    {
        isPalindrome(str, start + 1, end - 1); //calling the function again
        isPalindromeTrue = TRUE; //will be used after all itertions
    }
    if ((strlen(str) - 1) % 2 == 0) //checking if the string is even
    {
        if (str[(strlen(str) - 1) / 2 - 1] != str[(strlen(str) - 1) / 2])
        {
            isPalindromeTrue = FALSE; //will be used after all itertions
        }
    }


    return isPalindromeTrue;
}