Brick items are laying down concrete tiles, and concrete items are laying down brick tiles.

Not a bug. This is by design. I like the look of the vanilla tiles better. Concrete is completely optional to make, unless you want it's tiles.

Ah. I see. Would be nice to include a setting to disable that. I've been using concrete because I need to burn through all of my excess stone, and also don't like the look of the Angel's version.

If you have extra crushed stone, you can always just make it into Mineral Sludge.