Cache not clearing, what am I missing?

private bool IsAllowed(string controllerName, string actionName, string ipAddress)
{
    var isAllowed = true;
    var maxRequests = 3;
    var timeframeMins = 3;
    var cacheKey = $"{controllerName}-{actionName}-{ipAddress}";  
                
    MemoryCache cache = MemoryCache.Default;
    CacheItemPolicy policy = new CacheItemPolicy
    {
        AbsoluteExpiration = DateTimeOffset.UtcNow.AddMinutes(timeframeMins),
        Priority = System.Runtime.Caching.CacheItemPriority.Default,
    };

    if (cache.Get(cacheKey) == null)
    {
        cache.Add(cacheKey, 1, policy);
    }
    else
    {
        var hitCount = (int)cache.Get(cacheKey);
        hitCount++;
        cache[cacheKey] = hitCount;

        if (hitCount > maxRequests)
        {
            isAllowed = false;
        }
    }

    return isAllowed;
}

HttpContext.Current.Cache.Insert(cacheKey,
                   1,
                   null,
                   DateTimeOffset.UtcNow.AddMinutes(timeframeMins),
                   Cache.NoSlidingExpiration,
                   CacheItemPriority.Low)

...

HttpContext.Current.Cache[cacheKey] = hitCount;