Custom smart search index not indexing content

I crawl and get pages. If page is of certain class I get associated data through an api call.

var data = AsyncHelper.RunSync(async () => await GetDataAsync(id));

Whenever I use AsynHelper indexed content is 0 sometimes but 2(expected) sometimes.GetDataAsync() actually returns data each time.If manually construct 2 data I can see indexed content as 2 each time.

Can anyone clarify on this. Thanks.