Alas I never did define if nap happens when it is charging as I do not have a home charging station someone else can answer this question if they have had a successful nap fix which happened during the charge period.
My theory is your car goes in to a light nap when you exit the car. A little deeper when you lock the doors. From that point on the longer the deeper the nap until it reaches a NAP state. After that more does not help.
Alas I have not had enough problems to run tests to define how long a nap is needed to fix each problem.
What I suspect is happening is that modules are powering down / capacitors are discharging and sub systems final enter a dormant state. Like any electric device it takes time. If you in plug and immediately re plug in a router or a computer sometimes not all sub modules have powered down. Of course for most devices 10 seconds is more than enough but the car is a lot bigger and … well Volvo never said.
If you have a nap solvable problem and some time please let it nap for 1 min. 2 min. 4 etc and see which works then let us all know