Hi. I have an NPC with a very simple package. She should just stand in position at at an XMarkerHeading, facing the direction of the heading.

However she always takes another NPC's seat instead.

I copied the New NPCs Package from Hulda's Package, and I did target the correct object ( the xmarkerheading ).

Why would this NPC be compelled to sit down, even after I've disabled "sitting"?

There is no issue with any condition,because the package has no conditions. It's just true.

Any thoughts?

If they're sitting then they're using another package, possibly from the master package list. Check your package has the must complete flag ticked and that its always valid for time/day etc.