Drawing maps shows white textures instead of images

[Woukie]

Describe the bug
On drawing thumbnails for maps in the level toggle menu, it appears that textures don't load fast enough for a screenshot to load.

To Reproduce
Steps to reproduce the behavior:

1. Go to the 'Toggle Levels' menu
2. Hit the 'Redraw All' button
3. Maps that use images that aren't cached will use white textures instead

Expected behavior
Thumbnails should be the same as images seen in-game

Current Workaround
Load all the maps to cache images, then draw them.