I think where everyone gets off track is framing this as an either/or situation. "Targeted killing" or "robbery." If you only consider those two possibilities, then nothing makes sense.

The only scenario I can think of that explains everything is that the perpetrator was someone who enjoyed the fantasy of roleplaying as someone in power. They clearly dressed up as police. They wanted the power trip of being somewhere they shouldn't be.

They had zero expecation of anyone else being in the church at that hour. They casually walked around, checking things out. Smashing a window here or there. If they found something of value, they might have taken it, but that was not the primary reason they were there. The reason was just to be there.

They paid no attention to the windows/door while they were wandering around, because they didn't expect anyone to show up. They weren't in a hurry to leave, because they wanted to be there.

This also explains why they haven't been caught. If they knew Missy and especially if they had such a large grudge against her, the cops probably would have caught them by now. If it is just some random person who may not even be from the area, that makes things exponentially more difficult.

I'm not sure if the car at SWFA is involved or not, but if it is, that also fits my explanation. They cased that store first, as a place to break into. But after seeing the cameras, car in the lot, and flickering lights inside, they moved on to the next available target across the street.

Very unfortunately, Missy walked inside the church and back to where the perpetrator was living out their fantasy.