I have tried a couple different extensions and/or power-up and for some reason, none of them that set backgrounds colors (usually based on 1st label assigned) for cards sem to be working. Instead the card background remains white and the thin label sliver of color is displayed. I have deactivated and uninstalled all other Trello extensions and power-ups. Selecting a card cover color and choosing the full card option DOES work.
Any ideas?