たぶんこの辺が原因 | Codetter（こーどったー）

        public void RefreshEntrysCache()
        {
            this.EntrysCache.Clear();
            Observable.Repeat(this.CreateHatenaDiaryClient())
                .Select((client, i) => client.GetEntrys(i + 1))
                .TakeWhile(_ => _.Any().First())
                .SelectMany(_ => _)
                .Subscribe(_ => MergeOrAddEntry(_, this.EntrysCache));
        }

        public void RefreshDraftsCache()
        {
            this.DraftsCache.Clear();
            Observable.Repeat(this.CreateHatenaDiaryClient())
                .Select((client, i) => client.GetDrafts(i + 1))
                .TakeWhile(_ => _.Any().First())
                .SelectMany(_ => _)
                .Subscribe(_ => MergeOrAddEntry(_, this.DraftsCache));
        }