It looks like the API response for placements has recently changed: https://developer.foursquare.com/docs/explore#req=venues/categories
Now the “icon” field returns only “prefix” and “suffix” instead of “prefix”, “sizes” and “name”. To load the category icon, you need to combine the prefix + "bg_32" + suffix, replacing 32 with whatever size you want: 32, 44, 64, 88, 256.
source share