Why is Orca adding walls in the middle of top layers that are not the absolute top layer but exposed as a top surface?

[GrolarBear]

Hopefully, you can see the picture, I've run into this before, where if the surface is not the final top layer (if it's the top layer of a feature with nothing above it), it adds some random walls in the layer (look in some of the letters like the C, A, D but not the I and L). There are no details underneath that have that shape, those walls are only one layer thick.

Other times it hasn't been a problem, but in this case, I'm floating chrome paint into those details and the uneven surface is VERY obvious in the final finish, it both changes the reflection in the paint surface and causes the paint to bleed into the walls differently causing the letter to have a fat spot, to look like I splashed some of the paint up on the walls.