When you open a message the Category is listed at the top above the message except for the Smalltalk category.
The Smalltalk category also does not appear in the category column on https://talk.restarters.net
Fixed. Thanks for flagging Panda 
Here’s what was happening: Small Talk was just a modified uncategorised category, meaning it didn’t behave like a normal category. I’ve made it into a proper category now.
Thank you. I suggest you prevent the posting of uncategorised messages. It is confusing when in a message and trying to figure out which category it belongs to.
I agree. In fact, it’s already done!