Unwanted Matte in PNG Export

[Fizmarble]

I started this file on iPad and had this matte problem, so I switched to PC where I'm more proficient. You can see in the Export window that my file has a white matte. The artboard is 3000 x3000, and that's the export size as well. Unfortunately, the export shrinks my image down and adds a border that appears in the final image. Prior to this, the export was trying to export at 3125 x3125px, which is wrong again, because that's not the artboard size. If I change the matte color, the white border becomes that color. But I don't want a border at all. Any ideas?

[Old Bruce]

Would help if you could expand the Artboard "Album Art..." so as to see what is going on in there. At first glance this looks like you have included the bleed, which you haven't.

[Fizmarble]

Do you mean expand the layers under the artboard? My background image (the brick wall) extends beyond the artboard to the left. But everything else is slammed up against the artboard edges.

If I copy the contents of the problem artboard and past them into the original artboard (same size, 3000 x 3000), it previews and exports correctly.

[R C-R]

2 hours ago, Fizmarble said:

The artboard is 3000 x3000

Why is its X position 3296 px?

[Old Bruce]

20 hours ago, Fizmarble said:

Do you mean expand the layers under the artboard?

In your screenshot, click on the little triangle so we can see the layers on the artboard.