I've been using labels without any trouble. I could see them on cards in lists. Clicking on the label toggled text on and off. But I've done something that caused none of my labels to be displayed on cards in lists.
I can still see and set labels when I view a full card, but in lists themselves, there is no sign of them.
Here's a label on a card:

Here's the card in a list:

No sign of the label, with or without text.
What do I need to do to display the labels again?