V lags I. Meaning, volt is delayed by 90 deg by I which takes current to charge up that cap to see voltage rise. So voltage rises and falls by 90 degrees.
BTW, capacitor DOES not pass current. It is used to isolate two circuits (used in signal transfer) and to buffer & smooth voltage that circuit requiries.
Also there is other circuits that uses the C constant of a cap to generate sawtooth of some types. As well as paraola waveform ampified from very weak ripple off a capacitor of low frequency for example to shape the high freq component (ie pincushion).
When you have to fix, much of circuits depends on ESR of electrolytics. Once ESR is too high, circuit operates irratically or stop working, or worse blown up. So get a bob parker's ESR meter for this.