Solved it, thank you!
Hello everyone. For a few while I’ve been looking for solutions concerning a texture packing problem.
After loading the level, the textures are packed into a texture atlas (this is the only time that they are packed). The smallest mip maps of the generated texture atlas are completely black pixels. This may be why the furthest objects appear as as series of shimmering black dots, when the original texture is gray. The result looks rather ugly.
Now, if I lose window focus of the editor and return to it, large areas close to the player become black (although the mip maps appear to stay the same in the inspector).
In addition, one edge of each triangle becomes stretched all of the sudden. There are streaks along this edge.
Disabling anisotropy increases the number of black areas close to the player, whether window focus was lost or not.
Are there any known bugs regarding generated textures? Is there a solution to this problem?
Thank you.
Have you tried turning on “Border Mipmaps” in the import settings? Not sure if this would help, but worth a try. It would be interesting to see some of the original textures and the resulting texture atlas.
“Against the Wall” is pretty cool btw 
Thanks aNTeNNa trEE! I actually managed to find a partial solution. After a month of attempting this on and off, I fixed it four hours after posting my question!
The problem was with the compressed texture formats. When packing compressed images (DXT1 or DXT5) the resulting atlas file is a bit messed up. I have been using compression for everything. All of the original files have to be set to 16 bit or better for the atlas to be constructed properly. It will give my game a bit of a memory hit, but at least it works now.
The textures stretching at the edges when focus is taken away? That’s because one of the textures, the detail map, was of a different resolution from the diffuse and normal maps. Glad that I posted here regardless, it forced me to take inventory of what I did try and what I didn’t.