free stack function errors normally, but not when setting breakpoint - c

Question

I'm trying to create a stack using a dynamic array and I'm getting an error when I try to run the DeleteStack() function, however, if I set a breakpoint before the function and run the main program up till that point, then continue past it, it executes properly. Would someone please tell me what I'm doing wrong and why I'm seeing this behavior?
main.c:
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include "dynamic_array_stack.h"
int main() {
// create stack
DynArrayStack *S = CreateStack();
// fill stack
for (int i = 1; i <= 10; i++)
Push(S, i);
// try pushing past capacity, no error (realloc's)
Push(S, 42);
// top of stack
printf("Top of stack is %d\n", Top(S));
// pop all elements of stack
while (Top(S) != INT_MIN) {
printf("%d\n", Pop(S));
}
// delete stack, check pointer again
DeleteStack(S);
return 0;
}
dynamic_array_stack.h:
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
typedef struct dynarraystack {
int top;
int capacity;
int *array;
} DynArrayStack;
DynArrayStack* CreateStack() {
DynArrayStack* S = malloc(sizeof(DynArrayStack));
if (!S) {
printf("Error: Could not create stack.\n");
return NULL;
}
S->capacity = 1;
S->top = -1;
S->array = malloc(S->capacity * sizeof(int));
if (!S->array) {
printf("Error: could not create stack.\n");
return NULL;
}
return S;
}
int isFullStack(DynArrayStack *S) {
return (S->top == S->capacity-1);
}
void DoubleStack(DynArrayStack *S) {
S->capacity *= 2;
S->array = realloc(S->array, S->capacity);
}
void Push(DynArrayStack *S, int data) {
if (isFullStack(S))
DoubleStack(S);
S->array[++S->top] = data;
}
int isEmptyStack(DynArrayStack *S) {
return S->top == -1;
}
int Top(DynArrayStack *S) {
if(isEmptyStack(S))
return INT_MIN;
return S->array[S->top];
}
int Pop(DynArrayStack *S) {
if (isEmptyStack(S)) {
printf("Array is empty. Returning INT_MIN.\n");
return INT_MIN;
}
return S->array[S->top--];
}
void DeleteStack(DynArrayStack *S) {
if (S) {
if (S->array)
free(S->array);
free(S);
printf("Stack deleted.\n");
}
}
edit: Actually it only does not error if I set two breakpoints, one before the while loop (so I step through it manually), and another before the DeleteStack() function. Still confused though.