We know how it works, we just don’t yet understand what is going on under the hood.

In short, quantum effects can be very obvious with small systems. The effects generally get averaged out over larger systems. A measurement inherently entangled your small system with a much larger system diluting the effect.

The blind spot is that we don’t know what a quantum state IS. We know the maths behind it, but not the underlying physics model. It’s likely to fall out when we unify quantum mechanics with general relativity, but we’ve been chipping at that for over 70 years now, with limited success.