That's your view about the mechanics - gravity is 100% correct - its a big unsolved problem.. On this forum we are humble enough to say - we don't know if there are unanswered questions or not. I personally, with regard to standard QM, do not think there is. But I may be wrong.IBeyond the obvious need for gravity to be unified there are still yet unanswered mechanics involved in QM.
To be honest you will get a lot further in physics by taking my attitude ie I think I know the answer but I may be wrong. In fact that's the essence of science as explained by the master himself - Feynman:
Science is guess, experiment, guess, over and over. If experiment does not say what your guess says - then its wrong. It's that simple. You can have all sorts of opinions such as 'there are still yet unanswered mechanics involved in QM.' - but unless you can put them to the test then its so much hot air.
There is an old joke in physics. Whatever happened to so and so - he looked so promising. He became primarily concerned with what QM means. The response was - then he is lost. If you become overly worried by that you too will be lost.. That's why Einstein was lost in his later years - he had a certain view that may indeed be correct - but it was not testable so he really got nowhere - at least by his lofty standards - of course he still wrote interesting and provocative papers - but they didn't really lead anywhere, except in one case - Bell. I often wonder just what other great things he could have accomplished if he had more of the attitude I suggest.
There have been a number of excellent texts mentioned here. Just get the Feynman Lectures - study it and put your personal concerns to one side - and you will make progress - don't and you will get basically nowhere - just like everyone else who went down that path - even the great Einstein.