From the Command Modern Operations update - Build 1121.4 changelog:
* The "Land cover" map layer now uses WebP format for the tiles (instead of PNG), which achieves much smaller file sizes.
I have just noticed that while the game creates a ~\Steam\Steamapps\common\Command - Modern Operations\WW\Cache\LandCover_300_webp\ folder and creates many 3, 4, 6, 7, 8, 9, 10, 11, 12 sub-folders, there is nothing in these sub-folders. No webp image is downloaded.
I am now using the latest beta 1121.4 on Steam (manual update, overwriting previous files).
Thanks, confirmed and we are looking into it.