I have implemented the IndexOperationComplete on a custom index. After its completed indexing I am doing the following:

                _examineManager.TryGetIndex(HiqhQIndexConstants.ExamineIndexName, out var highQIndex);

            LuceneIndex luceneIndex = (LuceneIndex) highQIndex;

            using (var reader = IndexReader.Open(luceneIndex.GetLuceneDirectory(), true))
            {
                var tags = _tagService.GetTags(HiqhQIndexConstants.IndexFieldAliases.Tags,
                    "__IndexType:highqfeeditem",
                    reader);

                _tagService.AddTags(tags, Constants.Site.HighQTagGroup);
            }

The issue i am having is that its getting the index but its empty, in theory it should not be empty. When I run this same code in a controller after building index it works.