In SPICE (not only Qspice), transient simulation (.tran) starts (i.e. at t=0s) with certain initial condition. In default, initial voltage/current conditions are calculated from bias point / DC operating point simulation (.op) [Operation point values not corresponding to plots (using PWL controlled DC supplies)]. In short, SPICE performed a .op simulation before .tran begin, as to take the initial condition value for .tran to be used.
For your circuit, DC operating point is to assume C1 fully charged over time, where V(X)=V1.
I think Qspice Help should describe IC as “not set” to prevent confusion for SPICE beginner.