Product Filters / Metafields Error: "! Missing Label"

[pcgofficial]

Trying to make the products filterable by feature, unfortunately I'm getting this error. Originally I thought maybe I'd used Multi-Line Text or something when a Single Line Text would be required or something but I used single line text. I've included images below, first of the error in the Filters dialog and second of what the features metafield looks like. 

Any help would be awesome.