Why are my components unconnected in the middle of the breadboard?
Normally, these breadboards are built exactly for what you're trying to do. And normally, it works, because there aren't many different lengths of pins on ICs.

If more force doesn't help (i.e. your IC just can't be pushed in further), I'm afraid all you could try is use a IC socket; but to be honest, that would sound like a lot of trouble considering the job of holding and connecting your IC is exactly what you use your breadboard for.

Considering that you had problems with a button, too, I'd say that stranger things have happened than breadboards with varying build quality :(