Google dances are usual occurrences, however I've been seeing strange things in SERPS recently, odd index counts being returned that change as you navigate paginated results or even changes by the day.
Massive throttling of search traffic with strange peaks and troughs, mostly traffic falling off a cliff while at the same time some non existent content is being ranked ?
With the escalating number of threads here and elsewhere discussing this their appears to be a distant lack of consistency right now with current updates, so the dust is well and truly in the air still.
Its a bit like walking on broken glass at the minute, so I'm inclined to stop walking and watch things unfold until we have something concrete and can clear the glass for a more comfortable journey.
The fact that google is returning results when using site:domain.com at least means that content is indexed and considered worthy of staying in the index. However, as far as answering the question about why its not ranking....no clue right now.....keep reading and listening and going over what you've done just to cover any probable or glaring mistakes.
Things are bound to become clearer eventually....sooner rather than later I hope.