All the tracks currently have a pink square in the top left of the multiplayer lobby, where there's normally a skewed cover image.

This is because there are no "skew" images in the mod files (2276098616\data\menu\textures).

DIY Solution

If you're using the mod offline (copied from Workshop to the Mods folder) you can simply copy and rename the "small" images like so:

env_asan_small_250x116 > env_asan_skew_182x70.bmap

The thumbnails will appear cropped at the bottom and right, but it looks better than a pink square :)

If you're really keen, you can convert the .bmap files to .png using Breckfest (GitHub), then crop/center/skew them properly with Photoshop (or similar), then convert them back again with Breckfest.