Play a face up, non-Duration Action card from the trash, leaving it there and turning it face down for the turn.
No that phrase only stops the card from being moved into play. What stops the card from moving itself is apparently that it has already Lost Track of itself due to being played from an unexpected location.
Necromancer stops the played card from being moved to "in play," and that's all it stops. However! A card that for example trashes itself from play is looking for itself in play, and won't move itself if it's not there.
As the quote you quote says, it's not because it's being played
from an unexpected location; it's because it wasn't moved into the play area when that happened. Vassal e.g. plays cards
from an unexpected location too, but since it plays them
to the play area no losing-track occurs.