2D map area not corresponding to 3D map

So I’m new to DroneDeploy and have made my first few maps.

So I’m currently mapping a small industrial estate. I use DD to plan and fly the mission from an iPad Air 2. I plot the area I want mapped, The estate is a square with essentially a car park in one corner which I don’t want mapped. So the area I want mapped is an L shape. I upload the images using Structure mode.
When the map comes back, the 2D map corresponds to the L shape that I plotted, but the 3D map includes most of the car park.

I have tried:
The exact same mission again plotted from scratch.
Changing the map selection area to exactly what I want immediately before uploading the photos.
Changing the map selection area to exactly what I want once the map is stitched.
These have all resulted in the 2D map mapping the area I want, but the 3D map showing the entire square.

Any ideas what I’m doing wrong?
If it’s not possible to do what I’m hoping, is it possible for someone with zero 3D object editing skills, to redact the area in some way?

This is the area I’m trying to map - the colour saturated L shape which is what the 2D map looks like:

This the 3D map that’s produced:

Thanks for any ideas.

Once you upload your photos are you readjusting the mapping area? I always get in the option to reshape the mapping area prior to the start of processing. In addition, and I have not tried this, could you filter out the pictures of the parking lot prior to uploading them to dronedeploy?

Yes I do readjust prior to uploading. It just seems strange that the 2D map is exactly as I specify without the car park yet the 3D map includes the car park.
I had thought to manuall remove the photos that contain the car park manually my concern is that, although the car park comprises only perhaps 30% of the map, probably at least 60% of the photos contain some of the car park so this would massively compromise the quality of the map?

Unfortunately we don’t support arbitrary shapes in our 3D models.

You won’t really see much difference in map quality. GIve it a go both ways and then you’ll have to edit the 3D model in some 3D modelling software.