When running a transient simulation, it is important to note that, by default, DC supply voltages start at their nominal level instead of ramping up from 0V.

But what if you need to test the power on behavior of your circuit?  Fortunately the solution is simple, though it is easy to miss. When you are setting up your transient simulation, make sure the “Start external DC supply voltages at 0V” box is checked:

You can confirm the setting is active by looking for the word “startup” in your simulation string: