I've simulated a very simple circuit, as follows.
It has a step-up signal as input. And signal "n2" is interesting.
The reason for this is that there is no DC path from n1 to ground (it's floating at DC), and so the simulator inserts a gmin resistor to ground. Since the default value of gmin is 1e-12 Siemens (1e12 ohms), you then have a 2 second time constant - if you simulate for 2 seconds you'll see it's down to 0.369mV (i.e. 63% of the way there, what you'd expect after a time constant).
In this trivial circuit, you could set the option gmin to 0 (this is generally not a good idea, as gmin conductances are there to aid convergence - having absolutely no path to ground means that there are an infinite number of solutions for the DC operating point, since a floating node could be anything; a high value like 1e12 ohms is not unrealistic in terms of leakage).